// #define _GLIBCXX_DEBUG // for STL debug (optional)
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;
using ll = long long int;
using int64 = long long int;
 
template<typename T> void chmax(T &a, T b) {a = max(a, b);}
template<typename T> void chmin(T &a, T b) {a = min(a, b);}
template<typename T> void chadd(T &a, T b) {a = a + b;}
 
int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};
const int INF = 1LL << 29;
const ll LONGINF = 1LL << 60;
const ll MOD = 1000000007LL;

void drop(string s) {
    cout << s << endl;
    exit(0);
}

int main() {
    ll L, R, M, K; cin >> L >> R >> M >> K;
    if(K == 0 or L % M == 0 or R % M == 0) {
        drop("Yes");
    }
    if(L/M != R/M) {
        drop("Yes");
    }
    ll sl = L * K;
    ll sr = R * K;
    if(sl % M == 0 or sr % M == 0) {
        drop("Yes");
    }
    if(sl/M != sr/M) {
        drop("Yes");
    }
    drop("No");
    return 0;
}