#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>

#define rep(i,n) for(i=0; i<n; ++i)
#define in(a) cin >> a
#define out(a,b) cout << a << b
using namespace std;
using lint = long long;

int main(void){
    int i, j, n, m, k, cnt = 0;
    int a, b, c;
    in(a);
    in(b);
    in(c);
    if(a==b&&a==c)  out(a,endl);
    else if(a==b||a==c||b==c){
        if(a==b)    out(c,endl);
        else if(a==c)   out(b,endl);
        else    out(a,endl);
    }
    else{
        rep(i,4){
            if(a!=i&&b!=i&&c!=i)    out(i,endl);
        }
    }

    return 0;
}