#include <bits/stdc++.h>
using namespace std;
 
int main() {
  int a, b, c;
  cin >>a>>b>>c;
  if(a==b==c){
    cout <<a;
  }
else if((a != b)&&(a!=c)&&(b!=c)){
  cout << 6-(a+b+c);
}
  else{
    if(a==b){
      cout <<c;
    }
    else if(a==c){
      cout <<b;
    }
    else if(b==c) {
      cout << a;
    }
  }
}