#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset

using namespace std;

int main() {

	int a, b, c;
	cin >> a >> b >> c;

	if (a == b && b == c) {
		cout << a << endl;
	}
	else if (a == b) {
		cout << c << endl;
	}
	else if (a == c) {
		cout << b << endl;
	}
	else if (b == c) {
		cout << a << endl;
	}
	else {
		switch (a + b + c) {
		case 3: cout << 3 << endl; break;
		case 4: cout << 2 << endl; break;
		case 5: cout << 1 << endl; break;
		case 6: cout << 0 << endl; break;
		}
	}

	return 0;

}