ac的，关注我(＾Ｕ＾)ノ~ＹＯ

#include<iostream>
using namespace std;
int main(){
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    long long e,f;
    e=a*b*c;
    f=d*1000;
    if(e>=f)cout<<"Yes";
    else cout<<"No";
    return 0;
}