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

int main(){
    long long int Vx, Vy, tmp, N, i;
    vector <long long int> kyori;
    long long int vx, vy, t;

    cin >> Vx >> Vy >> N;
    while(cin >> tmp){
        kyori.push_back(tmp);
    }
    vx = Vx*1000*100000000000/3600;
    vy = Vy*1000*100000000000/3600;
    for(i = 0; i < N - 1; i++){
        t = kyori[i]*100000000000*100000000000/vx;
        if(vy*t/100000000000 > kyori[i + 1]*100000000000){
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;
    return 0;
}