#include <bits/stdc++.h>
using namespace std;

void fast_io() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
}

int main() {
	fast_io();
	int n;
	cin >> n;
	vector<int> a(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	if (*min_element(a.begin(), a.end()) <= 1) {
		cout << "Yes" << endl;
	} else {
		cout << "No" << endl;
	}
}