#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

vector <vector<bool> > g;
vector <bool> nodes, bio;
bool solution=true, color=false;

int dfs (int node) {
    color= color==false ? true : false;
    nodes[node]=color;

    for (int i=0;i<g[node].size();i++)
            if (g[node][i]==1 && bio[i]==false) {
            bio[i]=true;
            dfs (i); }
    color= color==false ? true : false;
    }


void read (int n) {
    solution=true;
    int l;
    scanf ("%d", &l);

    nodes.clear (); g.clear (); bio.clear();
    nodes.resize (n, false);
    bio.resize (n, false);
    g.resize (n, nodes);

    for (int i=0;i<l;i++) {
        int a, b;
        scanf ("%d %d", &a, &b);
        g[a][b]=g[b][a]=true;
    }
    bio[0]=true;
    dfs (0);

    for (int i=0;i<n-1;i++) {
        for (int j=i+1;j<n;j++) {
            if (g[i][j]==true && nodes[i]==nodes[j]) solution=false; } }
}

int main () {
        //freopen ("readfile.in", "r", stdin);
    int n;

    while (scanf ("%d", &n)==1 && n!=0) {
            read (n);
           printf (solution==false ? "NOT BICOLORABLE.\n" : "BICOLORABLE.\n");
    }
return 0; }