C - Rectangle

#include <stdio.h>
#include <stdlib.h>

int main()
{
   int Ax, Ay, Bx, By, a, b, S;

   printf("Coordinate of point A: ");
   printf("x: ");
   scanf("%d", &Ax);
   printf("y: ");
   scanf("%d", &Ay);

   printf("Coordinate of point B: ");
   printf("x: ");
   scanf("%d", &Bx);
   printf("y: ");
   scanf("%d", &By);

   a = Bx - Ax;
   b = By - Ay;

   S = a * b;

   printf("The area is: %d", S);


    return 0;
}