Naming changes.

Java/lab_1/lab_1.java

@@ -0,0 +1,34 @@
+import java.util.Scanner;
+
+public class lab_1 {
+    
+    public static int protectedInput(String variable_to_read, Scanner input) {
+        int read_variable;
+        do {
+            try {
+                System.out.printf("Enter %s: ", variable_to_read);
+                read_variable = input.nextInt();
+                break;
+            } catch (Exception e) {
+                System.out.printf("%s must be an integer.\n", variable_to_read.toUpperCase());
+                input.nextLine();
+            }
+        } while (true);
+        return read_variable;
+    }
+
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+
+        final int n = protectedInput("n", input);
+        final int m = protectedInput("m", input);
+        final int a = protectedInput("a", input);
+        final int b = protectedInput("b", input);
+
+        input.close();
+
+        float s = ((float) (b + m) / 2) * (m - b + 1) * (n - a + 1);
+
+        System.out.println("S = " + s);
+    }
+}