#include <iostream>
#include <queue>
#include <utility>
#include <vector>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m; cin >> n >> m;
    vector<pair<int, int>> edges(m); vector<vector<int>> g(n);
    for (auto &[u, v] : edges) {
        cin >> u >> v; --u; --v; g[u].push_back(v); g[v].push_back(u);
    }
    vector<int> color(n, -1); queue<int> q; color[0] = 0; q.push(0);
    while (!q.empty()) {
        int u = q.front(); q.pop();
        for (int v : g[u]) {
            if (color[v] == -1) color[v] = color[u] ^ 1, q.push(v);
            else if (color[v] == color[u]) { cout << "NO\n"; return 0; }
        }
    }
    cout << "YES\n";
    for (auto [u, v] : edges) cout << (color[u] == 0 ? '0' : '1');
    cout << '\n';
}