#include<iostream>
#include<list>
#include<vector>
#include <queue>
#include<cstdio>
#include<algorithm>
#include<string>
#include <cmath>
#include <cctype>
#define INFINI (1000 * 1000*1000)
using namespace std;


const int maxRepresentations=100000;
struct presentation
{
    int datedubet,datefin,salle,pos;
    bool operator < (const presentation& str) const
    {
        if(datedubet!=str.datedubet)
        return (datedubet < str.datedubet);
        return datefin<str.datefin;
    }
};
presentation planing[maxRepresentations+1];
int nbSalles,nbRepresentaions;
 list<presentation> salles[101];



int affectation(int debut,int fin)
{
    for(int index=1;index<=nbSalles;index++)
    {
        if(salles[index].empty())
        {
            presentation newone={debut,fin,index};
            salles[index].push_back(newone);
            return index;
        }
        else
        {
            list <presentation> :: iterator it;
            bool secondtest=true;
            for(it = salles[index].begin(); it != salles[index].end(); ++it)
            {
                if(!((*it).datedubet>=fin||(*it).datefin<=debut))
               {
                   secondtest=false;
                   break;
               }
            }

            if(secondtest)
            {
                 presentation newone={debut,fin,index};
            salles[index].push_back(newone);
            return index;
            }


        }
    }
    return -1;
}
bool acompare(presentation lhs, presentation rhs) { return lhs.pos < rhs.pos; }

int main()
{
    ios::sync_with_stdio(false);
    /////////////////////////////////////////////////////don't touch


    cin>>nbSalles>>nbRepresentaions;

    for(int i=1;i<=nbRepresentaions;i++)
    {
         cin>>planing[i].datedubet>>planing[i].datefin;
            planing[i].pos=i;
    }


    sort(planing+1,planing+nbRepresentaions+1);
     for(int i=1;i<=nbRepresentaions;i++)
     {
         int result=affectation(planing[i].datedubet,planing[i].datefin);
         if(result==-1)
            {
                 cout<<"NON"<<'\n';
                 return 0;
            }

            else
                planing[i].salle=result;

     }

    sort(planing+1,planing+nbRepresentaions+1,acompare);

    cout<<"OUI"<<'\n';
    for(int i=1;i<=nbRepresentaions;i++)
        cout<<planing[i].salle<<" ";


}