#include <bits/stdc++.h>
typedef long long int ll;
typedef long double ld;
using namespace std;
const long long int INF = 1e18;
const long long int mod = 1e9+7;
typedef pair<ll,ll> pairs;
typedef vector<pairs> p;


ll gcd(ll A,ll B){
    if (A%B==0)return(B);
    else return(gcd(B,A%B));
}

ll keta(ll N){
    int tmp{};
    while( N > 0 ){
        tmp += ( N % 10 );
        N /= 10;
    }
    N = tmp;
    return N;
}

vector<vector<ll>> combination(ll n, ll r){
    vector<vector<ll>> v(n + 1, vector<ll>(n + 1, 0));
    for(ll i=0;i<v.size();++i){
        v[i][0] = 1;
        v[i][i] = 1;
    }
    for(ll i=1;i<v.size();++i){
        for(ll j=0;j<i;++j){
            v[i][j] = (v[i - 1][j - 1] + v[i - 1][j]);
        }
    }
    return v;
}

bool kai(string S){
    bool flag = true;
    for(ll i=0;i<S.size()/2;++i){
        if(S[i] != S[S.size()-i-1]){
            flag = false;
            break;
        }
    }
    return flag;
}
// ---------------------------------------------

int main(){
    ll a, b, c, d;
    cin>>a>>b>>c>>d;
    ll flag = 0;
    while(a > 0 or c > 0){
        if(flag%2==0){
            c -= b;
        }else{
            a -= d;
        }
        flag++;
    }
    if(flag%2==0){
        cout<<"Yes"<<endl;
    }else{
        cout<<"No"<<endl;
    }
}