#include <bits/stdc++.h>
using namespace std;
using ll = int64_t;
#define rep(i,n) for (int i=0;i<(int)(n);i++)

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{
    rep(i,4){
      if(i!=a&&i!=b&&i!=c){
        cout<<i<<endl;
        break;
      }
    }
  }
}