fun solve(): Boolean {
    val (n, m) = readInts()
    val g = List(n) { mutableListOf<Int>() }
    repeat(m) {
        val (a, b) = readInts().map { it - 1 }
        g[a].add(b)
        g[b].add(a)
    }
    val nn = n.countTrailingZeroBits()
    if (n != 1 shl nn) return false
    if (g.any { it.size != nn }) return false
    val ans = IntArray(n) { 0 }
    val done = IntArray(n) { 0 }
    ans[0] = 0
    done[0] = 2
    val q = mutableListOf<Int>()
    for ((index, v) in g[0].withIndex()) {
        ans[v] = 1 shl index
        q.add(v)
        done[v] = 2
    }
    var pt = 0
    while (pt < q.size) {
        val v = q[pt++]
        done[v] = 2
        for (u in g[v]) {
            if (done[u] == 0) {
                done[u] = 1
                q.add(u)
            }
            if (done[u] != 2) {
                ans[u] = ans[u] or ans[v]
            }
        }
    }
    return g.indices.all { x -> g[x].all { y -> (ans[x] xor ans[y]).countOneBits() == 1 } }
}

fun main() {
    println(if (solve()) "yes" else "no")
}

private fun readInt() = readln().toInt()
private fun readLongs() = readStrings().map { it.toLong() }
private fun readStrings() = readln().split(" ")
private fun readInts() = readStrings().map { it.toInt() }