#include <bits/stdc++.h>
using namespace std;
int a[4];
int main() {
  cin >> a[1] >> a[2] >> a[3];
  sort(a + 1, a + 4);
  if (a[1] == a[2])
    cout << a[3] << endl;
  else
    cout << a[1] << endl;
}
