#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000000 + 7;
const long long MOD1 = 998244353;
long long mod(long long x) { return (x % MOD + MOD) % MOD; }
long long mul(long long a, long long b) { return mod(mod(a) * mod(b)); }
string itos(long long s) {
  string str = to_string(s);
  return str;
}
long long stoi2(string s) {
  long long a = atoi(s.c_str());
  return a;
}
long long powerm(long long a, long long b, long long MOD) {
  a %= MOD;
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return res;
}
long long power(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b & 1) res = res * a;
    a = a * a;
    b >>= 1;
  }
  return res;
}
bool isSubSequence(string str1, string str2, int m, int n) {
  if (m == 0) return true;
  if (n == 0) return false;
  if (str1[m - 1] == str2[n - 1])
    return isSubSequence(str1, str2, m - 1, n - 1);
  return isSubSequence(str1, str2, m, n - 1);
}
bool ispalindrome(long long len, string str) {
  for (int i = 0; i < len / 2; i++) {
    if (str[i] != str[len - 1 - i]) {
      return false;
    }
  }
  return true;
}
inline bool isPowerOfTwo(long long x) {
  return ((1LL << (long long)log2(x)) == x);
}
long long isprime(long long N) {
  if (N < 2 || (!(N & 1) && N != 2)) return 0;
  for (long long i = 3; i * i <= N; i += 2) {
    if (!(N % i)) return 0;
  }
  return 1;
}
vector<long long> factor;
void factors(long long n) {
  for (long long i = 1; i <= sqrt(n); i++) {
    if (n % i == 0) {
      if (i == n / i)
        factor.push_back(i);
      else {
        factor.push_back(i);
        factor.push_back(n / i);
      }
    }
  }
  sort((factor).begin(), (factor).end());
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return (a / gcd(a, b)) * b; }
bool isvalid(long long i, long long j, long long n) {
  if (i >= 0 && i < n && j >= 0 && j < n) return true;
  return false;
}
long long dx[8] = {0, 1, 1, 1, 0, -1, -1, -1};
long long dy[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
long long binarytodecimal(string n) {
  string num = n;
  long long dec_value = 0;
  long long base = 1;
  long long len = num.length();
  for (int i = len - 1; i >= 0; i--) {
    if (num[i] == '1') dec_value += base;
    base = base * 2;
  }
  return dec_value;
}
string dtb(long long n) {
  string s = "";
  while (n > 0) {
    if (n % 2 == 0)
      s.push_back('0');
    else
      s.push_back('1');
    n /= 2;
  }
  reverse((s).begin(), (s).end());
  return s;
}
vector<long long> seive;
void Seive() {
  const long long maxn = 1e6 + 5;
  seive.resize(maxn);
  for (long long i = (long long)0; i < (long long)maxn; i++) seive[i] = i;
  for (long long i = 2; i <= maxn; i += 2) seive[i] = 2;
  seive[1] = -1;
  seive[0] = -1;
  for (long long i = 3; i <= maxn; i += 2)
    if (i == seive[i])
      for (long long j = i * i; j < maxn; j += i)
        if (seive[j] == j) seive[j] = i;
}
vector<long long> ad[200005];
long long n, m;
long long cl[200005], vis[200005];
long long bi(long long i, long long c) {
  vis[i] = true;
  cl[i] = c;
  for (long long k = 0; k < ad[i].size(); k++) {
    if (vis[ad[i][k]] == false) {
      if (bi(ad[i][k], c ^ 1) == false) return false;
    } else if (cl[ad[i][k]] == cl[i])
      return false;
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long T = 1;
  while (T--) {
    cin >> n >> m;
    vector<pair<long long, long long> > v;
    for (long long i = (long long)0; i < (long long)m; i++) {
      long long a, b;
      cin >> a >> b;
      v.push_back({a, b});
      ad[a].push_back(b);
      ad[b].push_back(a);
    }
    long long f = 1;
    for (long long i = (long long)1; i < (long long)n + 1; i++) {
      if (!vis[i]) f = bi(i, 0);
      if (f == 0) break;
    }
    if (f == 0) {
      cout << "NO\n";
      return 0;
    }
    map<long long, long long> mp;
    for (long long i = (long long)1; i < (long long)n + 1; i++) {
      if (cl[i] == 0) mp[i] = 1;
    }
    string ans;
    for (auto x : v) {
      f = x.first;
      if (mp[f] == 1)
        ans.push_back('0');
      else
        ans.push_back('1');
    }
    cout << "YES\n";
    cout << ans;
  }
}
