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

void Solve()
{
    double X,Y,pre,later,secX,secY,OneMaterX;
    int N;
    
    cin >> X >> Y >> N >> pre;
    
    secX = (X * 10 / 36);
    secY = (Y * 10 / 36);
    OneMaterX = 1/secX;
    
    for(int i = 1; i < N ; ++ i) 
    {
        cin >> later;
        
        if((pre * Y) > later * X )
        {
            cout << "NO" << endl;
            return;
        }
        
        pre = later;
    }
    
    cout << "YES" << endl;
}

int main(void){
    
    ios::sync_with_stdio(0);
    cin.tie(0);
    Solve();
    return 0;
}