#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
istream& operator>>(istream& in, pair<T1, T2>& a) {
  in >> a.first >> a.second;
  return in;
}
template <typename T1, typename T2>
ostream& operator<<(ostream& out, pair<T1, T2> a) {
  out << a.first << " " << a.second;
  return out;
}
template <typename T, typename T1>
T amax(T& a, T1 b) {
  if (b > a) a = b;
  return a;
}
template <typename T, typename T1>
T amin(T& a, T1 b) {
  if (b < a) a = b;
  return a;
}
const long long INF = 1e18;
const int32_t M = 1e9 + 7;
const int32_t MM = 998244353;
const long long N = 2e5 + 5;
vector<long long> v[N];
pair<long long, long long> e[N];
long long vis[N];
long long group[N];
void dfs(long long z, long long g) {
  group[z] = g;
  vis[z] = 1;
  for (long long x : v[z]) {
    if (vis[x]) {
      if (group[x] == group[z]) {
        cout << "NO";
        exit(0);
      }
      continue;
    }
    dfs(x, 3 - g);
  }
}
void solve() {
  long long n, m;
  cin >> n >> m;
  for (long long i = 0; i < m; i++) {
    long long x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
    e[i] = {x, y};
  }
  dfs(1, 1);
  cout << "YES\n";
  for (long long i = 0; i < m; i++) {
    if (group[e[i].first] == 1) {
      cout << 0;
    } else {
      cout << 1;
    }
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) solve();
  return 0;
}
