#define _CRT_SECURE_NO_WARNINGS
#define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 50;
const int M = N << 1;
int adj[N], nxt[M], to[M], col[N], ecnt;
bool vis[N];
inline void addEdge(int f, int t)
{
    nxt[ecnt] = adj[f];
    adj[f] = ecnt;
    to[ecnt] = t;
    ecnt++;
}
int main()
{
    memset(adj, -1, sizeof(adj));
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    for (int i = 0, u, v; i < m; i++)
    {
        cin >> u >> v;
        addEdge(u, v);
        addEdge(v, u);
    }
    queue<pair<int, int>> Q;
    for (Q.push(make_pair(1, 0)), vis[1] = true; !Q.empty(); Q.pop())
    {
        auto [x, c] = Q.front();
        for (int e = adj[x]; ~e; e = nxt[e])
            if (!vis[to[e]])
            {
                col[to[e]] = c ^ 1;
                vis[to[e]] = true;
                Q.push(make_pair(to[e], c ^ 1));
            }
    }
    bool flag = true;
    for (int i = 1; i <= n; i++)
        for (int e = adj[i]; ~e; e = nxt[e])
            if (col[to[e]] == col[i])
                flag = false;
    if (flag)
    {
        puts("YES");
        for (int i = 0; i < m; i++)
            putchar('0' + col[to[i << 1]]);
        putchar('\n');
    }
    else
        puts("NO");
    return 0;
}