#include<iostream>
using namespace std;
int a,b,c;
main()
{
	cin>>a>>b>>c;
	if(a==b&&b==c)cout<<a<<endl;
	else if(a==b||a==c||b==c)cout<<(a==b?c:a==c?b:a)<<endl;
	else cout<<6-a-b-c<<endl;
}