#include <bits/stdc++.h> using namespace std; typedef long long lint; #define rep(i,n) for(lint (i)=0;(i)<(n);(i)++) #define repp(i,m,n) for(lint (i)=(m);(i)<(n);(i)++) #define repm(i,n) for(lint (i)=(n-1);(i)>=0;(i)--) #define INF (1ll<<60) #define all(x) (x).begin(),(x).end() const lint MOD =1000000007; const lint MAX = 1000000; using Graph =vector<vector<lint>>; typedef pair<lint,lint> P; typedef map<lint,lint> M; lint fac[MAX], finv[MAX], inv[MAX]; void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (lint i = 2; i < MAX; i++) { fac[i] = fac[i - 1] * i % MOD; inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD; finv[i] = finv[i - 1] * inv[i] % MOD; } } long long COM(lint n, lint k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } lint primary(lint num) { if (num < 2) return 0; else if (num == 2) return 1; else if (num % 2 == 0) return 0; double sqrtNum = sqrt(num); for (int i = 3; i <= sqrtNum; i += 2) { if (num % i == 0) { return 0; } } return 1; } long long modpow(long long a, long long n, long long mod) { long long res = 1; while (n > 0) { if (n & 1) res = res * a % mod; a = a * a % mod; n >>= 1; } return res; } lint lcm(lint a,lint b){ return a/__gcd(a,b)*b; } lint gcd(lint a,lint b){ return __gcd(a,b); } int main(){ lint l,r,m,k; cin>>l>>r>>m>>k; l*=k; r*=k; if(k==0)cout<<"Yes"<<endl; else if(l+m-l%m<=r)cout<<"Yes"<<endl; else cout<<"No"<<endl; }