#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <queue>
#include <map>
#include <cmath>
#include <iomanip>
#include <set>
#include <cstdio>
#include <string>

using namespace std;

int main() {
  vector<int> cnt(4, 0);
  for (int i = 0; i < 3; i++) {
    int x;
    cin >> x;
    cnt[x]++;
  }
  for (int i = 0; i < 4; i++) {
    if (cnt[i] == 3) {
      cout << i << endl;
      return 0;
    }
  }
  bool ok = false;
  for (int i = 0; i < 4; i++) {
    if (cnt[i] == 2) {
      ok = true;
    }
  }
  if (ok) {
    for (int i = 0; i < 4; i++) {
      if (cnt[i] == 1) {
        cout << i << endl;
        return 0;
      }
    }
  }
  for (int i = 0; i < 4; i++) {
    if (cnt[i] == 0) {
      cout << i << endl;
      return 0;
    }
  }
  return 0; 
}