Added a Kotlin variation.

Java/lab_1/lab_1.java

@@ -7,14 +7,12 @@ public class lab_1 {
         do {
             try {
                 System.out.printf("Enter %s: ", variableToRead);
-                readVariable = input.nextInt();
-                break;
+                return input.nextInt();
             } catch (Exception e) {
                 System.out.printf("%s must be an integer.\n", variableToRead.toUpperCase());
                 input.nextLine();
             }
         } while (true);
-        return readVariable;
     }
 
     public static void main(String[] args) {
@@ -27,7 +25,7 @@ public class lab_1 {
 
         input.close();
 
-        float s = ((float) (b + m) / 2) * (m - b + 1) * (n - a + 1);
+        final float s = ((float) (b + m) / 2) * (m - b + 1) * (n - a + 1);
 
         System.out.println("S = " + s);
     }

Java/lab_1/lab_1.kt

@@ -0,0 +1,21 @@
+fun protectedInput(variableName: String): Int {
+    do {
+        try {
+            print("Enter $variableName: ");
+            return readln().toInt();
+        } catch (e: Exception) {
+            println("${variableName.uppercase()} must be an integer!");
+        }
+    } while (true)
+}
+
+fun main() {
+    val n: Int = protectedInput("n");
+    val m: Int = protectedInput("m");
+    val a: Int = protectedInput("a");
+    val b: Int = protectedInput("b");
+
+    val s: Float = (b + m).toFloat() / 2 * (m - b + 1) * (n - a + 1);
+
+    println("S = $s")
+}