#include <iostream>

int main(){
  int a, b, c;
  std::cin >> a >> b >> c;
  std::cout << (21-(a+b+c)) << '\n';
}
#include <bits/stdc++.h>
using namespace std;

int main() {
int a,b,c,d;
  cin >> a >> b >> c >> d;
  cout << b - c << endl;

}