#include<iostream>
using namespace std;
int main()
{
	int A, B, C; cin >> A >> B >> C;
	int ans;
	if (A == B && B == C)ans = A;
	else if (A != B && B != C && C != A)ans = 6 - (A + B + C);
	else ans = A ^ B ^ C;
	cout << ans << endl;
	return 0;
}