#include <iostream>

int main() {
    int n;
    size_t a, input;
    std::cin >> n >> a;
    size_t sum = n * a;
    for (int i = 0; i < n; i++) {
        std::cin >> input;
         sum -= input;
    }
    if (!sum) {
        std::cout << "YES" << std::endl;
    } else {
        std::cout << "NO" << std::endl;
    }
}