#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define INF 1000000000000000000
#define MOD 998244353
#define MAX 1000000


int main(){
  int a,b,c;
  cin>>a>>b>>c;
  if(a==b&&b==c){
    cout<<a<<'\n';
  }else if(a!=b&&b!=c&&c!=a){
    cout<<6-a-b-c<<'\n';
  }else{
    if(a==b){
      cout<<c<<'\n';
    }else if(b==c){
      cout<<a<<'\n';
    }else{
      cout<<b<<'\n';
    }
  }
}