#include <iostream>
using namespace std;
int addition (int a, int b){
  return (a+b);
}

int subtraction (int a, int b){
  return (a-b);
}

int operation (int x, int y, int (*functocall) (int, int)) {
    int g;
    g=(*functocall)(x,y);
    return (g);
  }

  int main() {
  int m,n;
  int (*minus)(int,int) = subtraction;

  m = operation (7,5,addition);
  cout<<"m =" << m <<endl; 
 
  n = operation (m,2,subtraction);
  cout<<"Da sottrazionem =" << n <<endl; 

  n = operation (20, m, minus);
  cout<<"m =" << n <<endl; 
  return 0;
  }