fun f(h: Long, w: Long, n: Long, k: Long): Boolean {
    val t = h * w
    return when {
        t <= n -> t==k
        (t%n==k) || (n==k&&t%n==0L) -> true
        else -> false
    }
}

fun main(args: Array<String>) {
    val (h,w,n,k) = readLine()!!.split(' ').map(String::toLong)
    println(if (f(h,w,n,k)) "YES" else "NO")
}