l,r,m,k=map(int,input().split())
saisho=l*k
saidai=r*k
okflag=0
if saidai-saisho+1>=m:
    okflag=1
else:
    for num in range(saisho,saidai+1):
        if num%m==0:
            okflag = 1
if k==0:
    okflag=1
if okflag:
    print('Yes')
else:
    print('No')