#include <bits/stdc++.h>

using namespace std;

int main() {
    int n, b;
    while(cin >> n >> b && n != 0 && b != 0) {
        vector<int> balls(b);
        vector<bool> numbers(n + 1, false);
        for(int i = 0; i < b; ++i) cin >> balls[i];
        for(int i = 0; i < b; ++i) {
            for(int j = i; j < b; ++j) {
                int currNum = abs(balls[i] - balls[j]);
                numbers[currNum] = true;
            }
        }
        bool ans = true;
        for(int i = 0; i <= n && ans; ++i) {
            ans &= numbers[i];
        }
        if(ans) cout << "Y" << endl;
        else cout << "N" << endl;
    }
    return 0;
}