fun main(args: Array<String>) {
    agc014b()
}

fun agc014b() {
    val (n, m) = readLine()!!.split(' ').map { it.toInt() }
    val abList = (1..m).map { readLine()!!.split(' ').map { it.toLong() } }
        .flatten()

    val all = abList.groupBy { it }.map { it.value.size }.all { it % 2 == 0 }

    val answer = if (all) "YES" else "NO"

    println(answer)
}
