#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
    int A,B,C;
    cin>>A>>B>>C;
    if(A == B && B == C) cout<<A<<endl;
    else if(A != B && B != C && A != C) cout<<6-A-B-C<<endl;
    else if(A == B) cout<<C<<endl;
    else if(A == C) cout<<B<<endl;
    else cout<<A<<endl;
}