diff --git a/.idea/compiler.xml b/.idea/compiler.xml
index fb7f4a8..b589d56 100644
--- a/.idea/compiler.xml
+++ b/.idea/compiler.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="CompilerConfiguration">
-    <bytecodeTargetLevel target="11" />
+    <bytecodeTargetLevel target="17" />
   </component>
 </project>
\ No newline at end of file
diff --git a/.idea/deploymentTargetDropDown.xml b/.idea/deploymentTargetDropDown.xml
new file mode 100644
index 0000000..3064f62
--- /dev/null
+++ b/.idea/deploymentTargetDropDown.xml
@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="deploymentTargetDropDown">
+    <runningDeviceTargetSelectedWithDropDown>
+      <Target>
+        <type value="RUNNING_DEVICE_TARGET" />
+        <deviceKey>
+          <Key>
+            <type value="SERIAL_NUMBER" />
+            <value value="R52R200X4FM" />
+          </Key>
+        </deviceKey>
+      </Target>
+    </runningDeviceTargetSelectedWithDropDown>
+    <timeTargetWasSelectedWithDropDown value="2023-05-03T19:34:02.904665521Z" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/kotlinc.xml b/.idea/kotlinc.xml
new file mode 100644
index 0000000..e1eea1d
--- /dev/null
+++ b/.idea/kotlinc.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="KotlinJpsPluginSettings">
+    <option name="version" value="1.7.20" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/misc.xml b/.idea/misc.xml
index bdd9278..9f71c83 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_11" default="true" project-jdk-name="Android Studio default JDK" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" project-jdk-name="jbr-17" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">
diff --git a/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt b/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
index d6bda8a..b5a9cee 100644
--- a/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
+++ b/app/src/main/java/meow/sweetbread/lincalc/MainActivity.kt
@@ -317,30 +317,34 @@ class MainActivity : AppCompatActivity() {
                 when (token.value) {
                     "+" -> {
                         tmp_buf = buffer.dropLast(ext.size - position + 2)
-                        val res: Token =
-                            if ((first is Double) and (second is Double))
-                                Token(
-                                    Tokens.Number,
-                                    (first as Double + second as Double)
-                                )
-                            else if ((first is String) and (second is Double))
-                                Token(
-                                    Tokens.Linear,
-                                    Linear(first as String, second as Double, 0.0)
-                                )
-                            else if ((first is Linear) and (second is Double))
-                                Token(
-                                    Tokens.Linear, Linear(
-                                        (first as Linear).name,
-                                        (first as Linear).add + (second as Double),
-                                        (first as Linear).mul
-                                    )
-                                )
-                            else
-                                Token(
-                                    Tokens.Linear,
-                                    Linear(second as String, first as Double, 0.0)
-                                )
+                        val res: Token = when (first) {
+                            is Double -> {
+                                when (second) {
+                                    is Double -> { Token(Tokens.Number, (first + second)) }
+                                    is String -> { Token(Tokens.Linear, Linear(second, first, 1.0)) }
+                                    is Linear -> { Token(Tokens.Linear,
+                                        Linear(second.name, second.add + first, second.mul))
+                                    }
+                                    else -> {Token(Tokens.Error, "")}
+                                }
+                            }
+                            is String -> {
+                                when (second) {
+                                    is Double -> { Token(Tokens.Linear, Linear(first, second, 1.0)) }
+                                    else -> { Token(Tokens.Error, "") }
+                                }
+                            }
+                            is Linear -> {
+                                when (second) {
+                                    is Double -> { Token(Tokens.Linear,
+                                        Linear(first.name, first.add + second, first.mul))
+                                    }
+                                    else -> { Token(Tokens.Error, "") }
+                                }
+                            }
+                            else -> {Token(Tokens.Error, "")}
+                        }
+
                         tmp_buf += res
                         tmp_buf += buffer.drop(position + 1)
                     }
@@ -500,7 +504,8 @@ enum class Tokens {
     Constant,
     Variable,
     Linear,
-    Quadratic
+    Quadratic,
+    Error
 }
 
 class Token(val type: Tokens, val value: Any) {
diff --git a/build.gradle b/build.gradle
index b2ebb1e..906770c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,6 +1,6 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 plugins {
-    id 'com.android.application' version '7.4.1' apply false
-    id 'com.android.library' version '7.4.1' apply false
+    id 'com.android.application' version '8.0.0' apply false
+    id 'com.android.library' version '8.0.0' apply false
     id 'org.jetbrains.kotlin.android' version '1.7.20' apply false
 }
\ No newline at end of file
diff --git a/gradle.properties b/gradle.properties
index c22da57..bb36cd2 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -21,4 +21,6 @@ kotlin.code.style=official
 # resources declared in the library itself and none from the library's dependencies,
 # thereby reducing the size of the R class for that library
 android.nonTransitiveRClass=true
-android.enableJetifier=true
\ No newline at end of file
+android.enableJetifier=true
+android.defaults.buildfeatures.buildconfig=true
+android.nonFinalResIds=false
\ No newline at end of file
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 07bbf9a..2ecd476 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 #Wed Nov 16 21:17:09 MSK 2022
 distributionBase=GRADLE_USER_HOME
-distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0-bin.zip
 distributionPath=wrapper/dists
 zipStorePath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME