#include <iostream>
#include <cassert>

int main() {
    int N;
    assert(std::cin >> N);
    assert(2 <= N and N <= 100000);
    for (int i = 0; i < N; ++i) {
        int x;
        assert(std::cin >> x);
        assert(0 <= x and x <= 2);
    }
}