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

using ll = long long;

int main()
{
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int N;
    cin >> N;
    vector<ll> A(N + 1);
    for (int i = 0; i <= N; i++)
    {
        cin >> A[i];
    }

    double average = 0;
    for (int i = 0; i <= N; i++)
    {
        average += A[i];
    }
    average /= N;

    if (average <= 50000)
    {
        cout << "Yes" << endl;
    }
    else
    {
        cout << "No" << endl;
    }
}