#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <iostream>
#include <iomanip>
#include <sstream>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;

int checkNode(int nodeNum, int lastColor, vector<int> * vertColor, vector< vector<int> > * biGraph)
{
	int i = 0, returnValue = 0;

	if(lastColor == 2){ (*vertColor)[nodeNum] = 1; }
	else { (*vertColor)[nodeNum] = 2; }

	for(i = 0; i < (*vertColor).size(); i++)
	{
		if(returnValue > 0){ break; }
		if((*biGraph)[nodeNum][i] == 1 && (*vertColor)[i] == 0)
		{
			returnValue += checkNode(i, (*vertColor)[nodeNum], vertColor, biGraph);
		} else if((*biGraph)[nodeNum][i] == 1 && (*vertColor)[i] == lastColor){ returnValue += 0; }
		else if((*biGraph)[nodeNum][i] == 1 && (*vertColor)[i] == (*vertColor)[nodeNum]){ return 1; }
		else if((*biGraph)[nodeNum][i] == 0){ returnValue += 0; }
	}
	return returnValue;
}

int main()
{
	int i, j, startVert, curVert, biNotBi;
	int numVert, numEdges, vert1, vert2;
	vector< vector< int > > biGraph;
	vector<int> tempVec;
	vector<int> vertColor; //0 = uncolored, 1 = black, 2 = red
	
	while(1)
        {
                cin >> numVert;
                if(numVert == 0){ break; }
		cin >> numEdges;

		for(i = 0; i < numVert; i++)
		{
			for(j = 0; j < numVert; j++)
			{
				tempVec.push_back(0);
			}
			biGraph.push_back(tempVec);
			vertColor.push_back(0);
			tempVec.clear();
		}

		for(i = 0; i < numEdges; i++)
		{
			cin >> vert1 >> vert2;
			biGraph[vert1][vert2] = 1;
			biGraph[vert2][vert1] = 1;
		}

		biNotBi = checkNode(0, 2, &vertColor, &biGraph);

		if(biNotBi != 0){ cout << "NOT BICOLORABLE" << endl; }
		else { cout << "BICOLORABLE" << endl; }

		biNotBi = 0;
		biGraph.clear();
		vertColor.clear();
	}

	return 0;
}