#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
int main(void) {
    int a, b, c;
    cin >> a >> b >> c;
    if(a == b and b == c) {
        cout << a << '\n';
    } else if(a != b and b != c and c != a) {
        cout << 6 - a - b - c << '\n';
    } else {
        cout << (a xor b xor c) << '\n';
    }
}