function pointer x + y

#include <iostream>
using namespace std;

double add (double x, double y)
{
    return x + y;
}

double calculate (double m, double n, double (*pf)(double, double))
{
    return (*pf)(m, n);
}


int main()
{
    double sum = 0;
    double a, b;
    cin >> a >> b;
    sum = calculate(a,b,add);
    cout << sum << endl;
    return 0;
}