题解

#include<bits/stdc++.h>
#define ll long long                                                        //防伪标识
#define MAXN 1005
#define maxn 10005
#define MAXM 10000
#define maxm 1000005
using namespace std;
int a,b,c,d;
int main(){
	cin>>a>>b>>c>>d;
	if(a*b*c >= d*1000) cout<<"Yes";
	else cout<<"No";
	return 0;
}