#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define fi first
#define se second
#define all(a) a.begin(),a.end()
int main(){
  vector<int> a(3);
  for(int &i:a) cin >> i;
  sort(all(a));
  if(a[0]==a[2]) cout << a[0] << "\n";
  else if(a[0]==a[1]) cout << a[2] << "\n";
  else if(a[1]==a[2]) cout << a[0] << "\n";
  else cout << 6-a[0]-a[1]-a[2] << "\n";
  return 0;
}