/*
 * Author: .-O_O-.
 */
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include<bits/stdc++.h>
using namespace __gnu_pbds;
using namespace std;
#define ll long long
#define pb push_back
#define vi vector<int>
#define rep0(a,b) for(int a=0;a<b;a++)
#define rep1(a,b) for(int a=1;a<=b;a++)
#define repp(a,b,c) for(int a=b;a<c;a++)
#define in insert
#define len length()
#define si size()
#define lb lower_bound
#define ub upper_bound
#define beg begin()
#define en end()
#define f first
#define s second
#define pr(a) cout<<a
#define pr2(a,b) cout<<a<<" "<<b<<"\n"
#define nx cout<<"\n"
#define int long long
//void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
                                                     
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]"<<endl;}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define deb(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define deb(x...)
#endif
const ll mod = 998244353;
const ll maxn = 1000005;
const ll mm = 1e+18;
void solve()
{
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    int x=1;
    while(1){
        if(x&1){
            c-=b;
            if(c<=0) break;
        }
        else{
            a-=d;
            if(a<=0) break;
        }
        x++;
    }
    if(x&1) cout<<"Yes";
    else cout<<"No";
}
signed main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    int t=1;
	//freopen("sp.txt","r",stdin);
    //srand(time(0));
    //cin>>t;
    for(int _i=1;_i<=t;_i++){
        //cout<<"Case #"<<_i<<": ";
        solve();
        //nx;
    }
    return 0;
}