#include <bits/stdc++.h>
#define REP(i, n) for(int i = 0;i < n;i++)
#define ll long long
using namespace std;
//typedef vector<unsigned int>vec;
//typedef vector<ll>vec;
//typedef vector<vec> mat;
typedef pair<int, int> P;
typedef pair<ll,ll> LP;
const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
const int INF = 1000000000;
const ll LINF = 1000000000000000000;//1e18
const ll MOD = 1000000007;
//const ll MOD = 998244353;
const double PI = acos(-1.0);
const double EPS = 1e-10;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
//template<class T> inline void add(T &a, T b){a = ((a+b) % MOD + MOD) % MOD;};


void solve(){
    ll L, R, M, K;
    cin >> L >> R >> M >> K;
    if(K == 0 || M == 1 || L == 0){
        cout << "Yes" << endl;
        return;
    }

    ll range = R - L + 1;
    if(range >= M){
        cout << "Yes" << endl;
        return;
    }
    L %= M;
    R %= M;
    if(L > R) swap(L, R);
    ll mi = L * K % M;
    ll ma = R * K;
    if(mi <= M && M <= ma) cout << "Yes" << endl;
    else cout << "No" << endl;
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    // int T; cin >> T; REP(t,T) solve();
}