#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll l, r, m, k;
    cin >> l >> r >> m >> k;
    l *= k, r *= k;
    int flag = 0;
    if(r - l + 1 >= m) flag = 1;
    if(r % m == 0 || l % m == 0) flag = 1;
    if(r % m < l % m) flag = 1;
    if(flag) yn;
    return 0;
}