#include <bits/stdc++.h>
using namespace std;

int main() {
  int a,b,c;
  cin >> a >> b >> c;
  if (a == b == c) {
  cout << a << endl;
  }
  else if (a == b || b == c || c == a) {
  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;
}