L, R, M, K = map(int,input().split())
if K == 0 or L == 0:
    print("Yes")
else:
    if (L*K)%M == 0 or (R*K)%M == 0:
        print("Yes")
    else:
        print("Yes" if (L*K)//M != (R*K)//M else "No")