#include<bits/stdc++.h>
#define REP1(i,n,m) for(int i=n;i<=m;i++)
#define REP2(i,n,m) for(int i=n;i>=m;i--)
using namespace std;
void YN(bool f){if(f){cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}}
int main(){
	int a,b,c;
	cin>>a>>b>>c;
	if(a==b&&b==c){
		cout<<a<<endl;
	}
	else if(a!=b&&b!=c&&c!=a){
		cout<<6-(a+b+c)<<endl;
	}
	else{
		if(a==b){
			cout<<c<<endl;
		}
		else if(b==c){
			cout<<a<<endl;
		}
		else{
			cout<<b<<endl;
		}
	}
	
	
	
}