/*
Author: Anas
Date: 17-09-2024
Time: 14:07:22
File: B_Three_Brothers.cpp
*/
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main()
{
ios::sync_with_stdio(false);
cin.tie(NULL);
ll t = 1;
// cin >> t;
auto Anas = [&]()
{
ll a, b;
cin >> a >> b;
vector<pair<ll, bool>> v = {{1, false}, {2, false}, {3, false}};
for (ll i = 0; i < 3; i++)
{
if (a == v[i].first)
{
v[i].second = true;
}
if (b == v[i].first)
{
v[i].second = true;
}
}
for (ll i = 0; i < 3; i++)
{
if (v[i].second == false)
{
cout << v[i].first;
break;
}
}
};
while (t--)
{
Anas();
}
return 0;
}
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