#include <stdio.h>
#define rep(i, n) for (i = 0; i < n; i++)

int main() {
    long long n, a;
    scanf("%lld %lld", &n, &a);
    long long i, x, s = 0;
    rep(i, n) {
        scanf("%lld", &x);
        s += x;
    }

    if ((double)(s / n) == (double)a) puts("YES");
    else puts("NO");
    return 0;
}