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

int main()
{
    long long N;
    cin >> N;
    N += 1;
    while (N < 10)
    {
        N /= 10;
    }
    if (N == 0)
    {
        cout << "Yes";
    }
    else
    {
        cout << "No";
    }
}