#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
#define REP(i,n) for(ll i=0;i<(n);i++)
#define ALL(v) v.begin(),v.end()
template<typename T> bool chmax(T &x, const T &y) {return (x<y)?(x=y,true):false;};
template<typename T> bool chmin(T &x, const T &y) {return (x>y)?(x=y,true):false;};
constexpr ll MOD=998244353;
constexpr ll INF=2e18;

int main(){
    int a, b, c; cin >> a >> b >> c;
    if(a==b&&b==c)
        cout << a << endl;
    else if(a==b)
        cout << c << endl;
    else if(b==c)
        cout << a << endl;
    else if(c==a)
        cout << b << endl;
    else
        cout << 6-a-b-c << endl;
    return 0;
}