Two Value Calculator

package calculator;

import java.util.Scanner;
public class Calculator {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int x, y, ans, ans2;
        char op, res;
//     Loops the program in case the user wishes to calculate multiple problems
        do
        {
         ans = 1;
         ans2 = 1;
//      Prints a list of supported operations
         System.out.println("-------------------------------");
         System.out.println("List of operations:\n");
         System.out.println("Addition: +\nSubtraction: -\nMultiplication: *\nDivision = /\nModulus: %\nFactorial: !");
         System.out.println("-------------------------------\n");
//      User input
         System.out.print("Enter first value: ");
         x = input.nextInt();
         System.out.print("Enter second value: ");
         y = input.nextInt();
         System.out.print("Enter operation: ");
         op = input.next().charAt(0);
//      Checks to see if an inputted operation is incorrect
         while((op != '+') && (op != '-') && (op != '*') && (op != '/') && (op != '%') && (op != '!'))
         {
             System.out.print("Unrecognized operation. Please re-enter: ");
             op = input.next().charAt(0);
         }
//      Checks to see if the user is trying to divide by zero
         while((op == '/') && (y == 0))
         {
             System.out.print("Cannot divide by 0. Please re-input second value: ");
             y = input.nextInt();
         }
//      Addition
         if(op == '+')
         {
             ans = x + y;
         }
//      Subtraction
         else if(op == '-')
         {
             ans = x - y;
         }
//      Multiplication
         else if(op == '*')
         {
             ans = x * y;
         }
//      Division
         else if(op == '/')
         {
             ans = x / y;
         }
//      Modulus Division
         else if(op == '%')
         {
             ans = x % y;
         }
//      Factorial
         else
         {
             for(int i = 1; i <= x; i++)
             {
                 ans = ans * i;
             }

             for(int w = 1; w <= y; w++)
             {
                 ans2 = ans2 * w;
             }

         }
//      Prints answer for factorial
         if(op == '!')
         {
             System.out.println("The factorial of " + x + " is " + ans + ".");
             System.out.println("The factorial of " + y + " is " + ans2 + ".");
         }
//      Prints answer if not a factorial
         else
         {
             System.out.println("The answer is " + ans + ".");
         }
//      Asks the user if they would like to reset the calculator and input another problem
         System.out.print("Would you like to reset? (y/n): ");
         res = input.next().charAt(0);
//      Checks for caps sensitive answers
         while((res == 'Y') || (res == 'N'))
         {
             System.out.print("This program is case sensitive. Please re-input in lowercase: ");
             res = input.next().charAt(0);
         }
//      Checks for responses other than yes or no
         while((res != 'y') && (res != 'n'))
         {
             System.out.print("Unrecognized response. Please re-enter: ");
             res = input.next().charAt(0);
         }
        }while(res == 'y');
    }

}