# coding: utf-8
# Your code here!
import sys
read = sys.stdin.read
readline = sys.stdin.readline 
readlines = sys.stdin.readlines

l,r,m,k = [int(i) for i in read().split()]

def check(a,b,m): # [a,b]に m の倍数？
    if a%m == 0: return True
    if b//m != a//m: return True
    return False

if check(l*k,r*k,m):
    print("Yes")
else:
    print("No")