P1-P5: rewrite to match current syllabus

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

P5.java

@@ -1,20 +1,27 @@
-import java.util.function.Consumer;
-
-class P5 {
-  public static void main(String[] _args) {
-      int sub[] = { 64, 91, 45 };
-      P5 obj = new P5();
-      int sum = 0;
-
-      for (int i = 0; i < sub.length; i++) {
-          obj.grade(sub[i], i + 1);
-          sum += sub[i];
-      }
-
-      System.out.println("Overall Percentage: " + (float) sum / 3 + "%");
-  }
-
-    void grade(int n, int s) {
-        System.out.println( "Subject " + s + " grade: " +  (char)( n >= 90 ? 'A' : n < 50 ? 'F' : 'A' + (9 - n / 10)));
+class MyException extends Exception {
+    public MyException(String message) {
+        super(message);
+    }
+}
+
+public class P5 {
+    public static void main(String[] args) {
+        try {
+            int result = divide(10, 0);
+            System.out.println("Result: " + result);
+        } catch (MyException e) {
+            System.out.println("My Exception: " + e.getMessage());
+        } catch (ArithmeticException e) {
+            System.out.println("Arithmetic Exception: " + e.getMessage());
+        } finally {
+            System.out.println("Finally block executed.");
+        }
+    }
+
+    public static int divide(int num1, int num2) throws MyException {
+        if (num2 == 0) {
+            throw new MyException("Division by zero not allowed.");
+        }
+        return num1 / num2;
     }
 }