Bicoloring

from collections import defaultdict
from functools import lru_cache
import threading
from sys import stdin,stdout,setrecursionlimit

setrecursionlimit(1 << 30)
threading.stack_size(1 << 27)


def main():
    
    while True:
        n= int(input())
        if not n:
            break
        l = int(input())
        graph = defaultdict(list)
        
        for _ in range(l):
            u, v = map(int, input().split())
            graph[u].append(v)
            graph[v].append(u)
 
        def dfs(node, color):

            visited[node] = color
            for neghibour in graph[node]:
                if neghibour in visited:
                    if visited[neghibour] == color:
                        return False
                else:
                    if not dfs(neghibour, 1 - color):
                        return False
            
            return True
        
        visited = {}
        res  = dfs(u, 1)
        print("BICOLOURABLE." if res else "NOT BICOLOURABLE.")

main_thread = threading.Thread(target=main)
main_thread.start()
main_thread.join()