#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const long long template_array_size = 1e6+100;
long long a[template_array_size];
long long b[template_array_size];
ll ans = 21;
void solve(){
	ll a,b,c;
	cin>>a>>b>>c;
	ans = ans - (a+b+c);

	cout<<ans<<"\n";
}
int main(){
	solve();
	return 0;
}
#include <iostream>
using namespace std;

int main()
{
    int X, Y, Z;
    cin >> X >> Y >> Z;

    double a = (double)Z * Y / X;
    int b = (int)a;
    if(a == b) {
        cout << b-1 << endl;
    } else {
        cout << b << endl;
    }

    return 0;
}