L,R,M,K = map(int,input().split())
if R-L+1>=M or K>=M:
    print("Yes")
else:
    L = L%M
    R = R%M
    if L>=R:
        print("Yes")
    else:
        k1 = (R*K)//M
        k2 = (L*K-1)//M
        if k1>k2:
            print("Yes")
        else:
            print("No")