#include <bits/stdc++.h>
using namespace std;
const long long INFL = 1LL << 60;
const long long INF = 1 << 30;
long long MOD = 1000000007;
vector<long long> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<long long> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};
void pres(double A, long long x = 10) {
  cout << fixed << setprecision(x) << A << endl;
}
void BinarySay(long long x, long long y = 60) {
  for (long long i = 0; i < (y); i++) cout << (x >> (y - 1 - i) & 1);
  cout << endl;
}
long long cnt_bit(long long x) { return __builtin_popcountll(x); }
long long pow_long(long long x, long long k) {
  long long res = 1;
  while (k > 0) {
    if (k % 2) res *= x;
    x *= x;
    k /= 2;
  }
  return res;
}
long long pow_mod(long long x, long long k) {
  long long res = 1;
  while (k > 0) {
    if (k % 2) {
      res *= x;
      res %= MOD;
    }
    x *= x;
    x %= MOD;
    k /= 2;
  }
  return res;
}
long long inverse(long long x) { return pow_mod(x, MOD - 2); };
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long x, long long y) { return x / gcd(x, y) * y; };
long long N, M;
vector<long long> E[200010];
vector<long long> col(200010);
bool odd_cycle(long long now = 0, long long from = -1, long long x = 1) {
  if (col[now] == 0) {
    col[now] = x;
    bool res = 0;
    for (long long to : E[now]) {
      if (to == from) continue;
      if (odd_cycle(to, now, -x)) res = 1;
    }
    return res;
  } else {
    if (col[now] == x)
      return 0;
    else
      return 1;
  }
}
void solve() {
  cin >> N >> M;
  vector<pair<long long, long long>> edge(M);
  for (long long i = 0; i < (M); i++) {
    long long a, b;
    cin >> a >> b;
    a--, b--;
    edge[i] = {a, b};
    E[a].push_back(b);
    E[b].push_back(a);
  }
  if (odd_cycle()) {
    cout << "NO" << endl;
    return;
  }
  cout << "YES" << endl;
  for (long long i = 0; i < (M); i++) {
    if (col[edge[i].first] == 1)
      cout << 1;
    else
      cout << 0;
  }
  cout << endl;
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  solve();
}
