#include <iostream>
using namespace std;

int addition (int a, int b);
int subtraction (int a, int b);
int operation (int x, int y, int (*functocall) (int, int));


  int main() {
  int m,n;
  int (*minus)(int,int) = subtraction;// minus puntatore alla funzione subtraction

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

  n = operation (20, m, minus);
  cout<<"Da minus: 20 - m  = " << n <<endl;

  return 0;

  }

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); //puntatore alla funzione functocall
    return (g);
  }