import std.stdio, std.string, std.conv, std.algorithm;
import std.range, std.array, std.math, std.typecons, std.container, core.bitop;


void main() {
    int n, m;

    scan(n, m);

    auto deg = new int[](n);
    auto adj = new int[][](n, 0);

    foreach (i ; 0 .. m) {
        int ai, bi;
        scan(ai, bi);
        adj[ai] ~= bi;
        adj[bi] ~= ai;
        deg[ai] ^= 1;
        deg[bi] ^= 1;
    }

    auto visited = new bool[](n);

    void dfs(int u) {
        visited[u] = 1;

        foreach (v ; adj[u]) {
            if (!visited[v]) {
                dfs(v);
            }
        }
    }

    foreach (u ; 0 .. n) {
        if (!adj[u].empty) {
            dfs(u);
            break;
        }
    }

    foreach (u ; 0 .. n) {
        if (!visited[u] && !adj[u].empty) {
            writeln("NO");
            return;
        }
    }

    deg.sort!"a > b"();

    if (n == 2) {
        writeln(deg == [1, 1] ? "YES" : "NO");
        return;
    }

    if (deg.startsWith([1, 1, 0]) || deg.startsWith([0])) {
        writeln("YES");
    }
    else {
        writeln("NO");
    }
}


void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}