#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include <iomanip>
using namespace std;

int main(){
    int a, b, c, d = 6;
    cin >> a >> b >> c;
    if (a == b && b == c) cout << a << endl;
    else if (a == b) cout << c << endl;
    else if (a == c) cout << b << endl;
    else if (b == c) cout << a << endl;
    else cout << d - a - b - c << endl;
}