#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;

ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;
    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}

long long mod_exp(long long b, long long e, long long m) {
    if (e > 0 && b == 0) return 0;
    long long ans = 1;
    b %= m;

    while (e > 0) {
        if ((e & 1LL)) ans = (ans * b) % m;
        e = e >> 1LL;
        b = (b * b) % m;
    }

    return ans;
}


int main()
{

    int Q;
    Q = 1;
    //cin >> Q;
    
    while (Q--) {
        
        double x, y;
        cin >> x >> y;
        int n;
        cin >> n;
        vector<double> tx(n+2), ty(n+2);
        for (int i = 0; i < n; i++) {
            double a;
            cin >> a;
            tx[i] = a/x;
            
            ty[i]= a / y;
            
            //cout << tx[i] << " " << ty[i] << endl;
        }
        for (int i = 0; i < n - 1; i++) {
            if (tx[i] < ty[i + 1])continue;
            cout << "NO"; return 0;
        }
        cout << "YES";

    }

    return 0;
}