#include <stdio.h>

int sum(int a, int b);

int subtract(int a, int b);

  

int main(void)

{
  p[0] = sum; // address of sum() 

  p[1] = subtract; // address of subtract() 

  int result;

  int i = 2, j = 2, op;

  

  printf("0: Add, 1: Subtract\n");

  do {

    printf("Enter number of operation: ");

    scanf("%d", &op);

  } while(op<0 || op>2);

  result = (*p[op]) (i, j);

  printf("%d", result);

  return 0;

}

int sum(int a, int b)

{

  return a + b;

}

int subtract(int a, int b)

{

  return a - b;

}