#include <bits/stdc++.h>
#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i < (n+1); ++i)
using namespace std;
using ll = long long;
const int INF = +100100100;
typedef pair<int,int> P;
const ll MO = 1000000007;

struct Mon{
    int h,d;
};

int main(){
    Mon x,y;
    int a,b,c,d;
    cin>>a >> b >> c >> d;
    x.h=a;x.d=b;y.h=c;y.d=d;
    int i = 0;
    while(x.h>0 && y.h >0){
        if(i%2==1){
            x.h-=y.d;
        }else{
            y.h-=x.d;
        }
        ++i;
    }
    if(i%2==0)cout<<"No"<<endl;
    else cout << "Yes" << endl;
    return 0;
}