#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <map>

#define ALL(x) (x).begin(),(x).end()
#define RALL(x) (x).rbegin(),(x).rend()
#define REP(i,a,n) for(int i = (a);i < (n);i++)
#define PI 3.14159265359
#define MOD 1000000007

using namespace std;

int main(){
    double x,y,n,Y = 0;
    string ans = "YES\n";
    cin >> x >> y >> n;
    REP(i, 0, n){
        int a;
        cin >> a;
        if(Y > a){
            ans = "NO\n";
        }
        Y = y*a/x;
    }
    cout << ans;
    return 0;
}