#include<iostream>
#include<vector>
#include<algorithm>
#define ep emplace
#define eb emplace_back
#define fi first
#define se second
#define all(x) (x).begin(),(x).end()
using namespace std;
typedef long long ll;
typedef pair<int,int>pi;
typedef pair<ll,ll>pl;
const int inf=1e9+7;
const ll INF=1e18;

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int a,b,c;
    cin>>a>>b>>c;
    if(a==b&&a==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
        cout<<(6-a-b-c)<<endl;
    return 0;
}