BiColoring

//In the Name of Allah Most Gracious, Most Merciful//
/*If you want something you've never had, you have  to do something you never did.*/

#include<bits/stdc++.h>
using namespace std;


#define pb push_back
#define ll long long
#define pii pair<int,int>
#define pll pair<ll,ll>
#define M 101007
#define INF 1e9
#define INFL 1e18
#define PI acos(-1)
#define mp make_pair

//const int fx[]= {+1,-1,+0,+0};
//const int fy[]= {+0,+0,+1,-1};
//const int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};   // Kings Move
//const int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};  // Kings Move
//const int fx[]={-2, -2, -1, -1,  1,  1,  2,  2};  // Knights Move
//const int fy[]={-1,  1, -2,  2, -2,  2, -1,  1}; // Knights Move


int gcd(int a, int b)
{
 return b ? gcd(b, a%b) : a;
}

int color[2*M+100];
bool visited[2*M+100];
vector<int>adj[2*M];


bool dfs(int node)
{
    for(int i=0;i<adj[node].size();i++)
    {
        int x=adj[node][i];
        if(visited[x]==false)
        {
            visited[x]=true;
            color[x]=!color[node];
            if(!dfs(x))
                return false;
        }
        else if(color[x]==color[node])
            return false;
    }
    return true;
}


int main()
{

   //  #ifndef ONLINE_JUDGE
   //    freopen("input.txt","r",stdin);
   //    freopen("output.txt","w",stdout);
  //   #endif
    int n,m;
    cin>>n>>m;
    vector<pii>v;
    for(int i=0;i<m;i++)
    {
        int x,y;
        cin>>x>>y;
        adj[x].pb(y);
        adj[y].pb(x);
        v.pb(mp(x,y));
    }
    memset(color,0,sizeof color);
    memset(visited,false,sizeof visited);
    visited[1]=true;
    bool ans=dfs(1);
    if(ans)
    {
        cout<<"YES"<<endl;
        for(int i=0;i<m;i++)
        {
            int x=v[i].first;
            int y=v[i].second;
            if(color[x]==0)
            {
                cout<<1;
            }
            else
            {
                cout<<0;
            }
        }
        cout<<endl;
        //cout<<endl;
    }
    else
    {
        cout<<"NO"<<endl;

    }
//#ifdef LOCAL_DEFINE
  //  cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
// #endif
///Before submit=>
///    *check for integer overflow,array bounds
///    *check for n=1
}