#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
long long max3(long long x, long long y, long long z) {
  return max(max(x, y), z);
}
long long min3(long long x, long long y, long long z) {
  return min(min(x, y), z);
}
const long long M = 2e5 + 10, M2 = 1e6 + 10, mod = 1e9 + 7, inf = 1e17 + 10;
void add(int& a, int b) {
  a += b;
  if (a >= mod) {
    a -= mod;
  }
}
int X[] = {0, 1, 0, -1};
int Y[] = {-1, 0, 1, 0};
long long power(long long x, long long n) {
  long long result = 1;
  while (n > 0) {
    if (n % 2 == 1) result = (result * x) % mod;
    x = ((x % mod) * (x % mod)) % mod;
    n = n / 2;
  }
  return result;
}
vector<vector<long long> > adj;
long long color[200001];
long long vis[200001];
void dfs(long long v) {
  for (auto u : adj[v]) {
    if (color[u] != -1) {
      if (color[u] == color[v]) {
        cout << "NO";
        exit(0);
      }
    } else {
      color[u] = color[v] ^ 1;
      dfs(u);
    }
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  adj.clear();
  adj.resize(n);
  for (long long i = 0; i < m; i++) {
    long long x, y;
    cin >> x >> y;
    x--;
    y--;
    vis[i] = x;
    adj[x].push_back(y);
    adj[y].push_back(x);
  }
  memset(color, -1, sizeof(color));
  for (int i = 0; i < n; i++) {
    if (color[i] == -1) {
      color[i] = 0;
      dfs(i);
    }
  }
  cout << "YES\n";
  for (long long i = 0; i < m; i++) {
    if (color[vis[i]])
      cout << 1;
    else
      cout << 0;
  }
  return 0;
}
