#include <stdio.h>
#include <bits/stdc++.h>
//%lld
typedef long long ll;
#define si(a) scanf("%d", &a)
#define sii(a, b) scanf("%d%d", &a, &b)
using namespace std;

int main(){
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    vector<int>grafo[1000];
    queue<int> fila;
    int cor[1000];
    int v, a, b, aux;
    bool c = true;
    while(cin>>v){
        if(v==0)break;
        else{
            c = true;
            for(int i = 0;i<v;i++){
                sii(a, b);
                grafo[a].push_back(b);
                grafo[b].push_back(a);
            }
            fila.push(0);
            cor[0] = 1;
            while(!fila.empty()&&c){
                aux = fila.front();
                fila.pop();
                for(int i = 0;i<grafo[aux].size();i++){
                    if(cor[grafo[aux][i]]==0){//nao ta pintado
                        if(cor[aux]==1)cor[grafo[aux][i]] = 2;
                        else cor[grafo[aux][i]] = 1;
                        fila.push(grafo[aux][i]);
                    }else{//ta pintado ja
                        if((cor[aux]==cor[grafo[aux][i]])||(cor[aux]==cor[grafo[aux][i]])){
                            c = false;
                            break;
                        }
                    }
                }
            }
            if(c)puts("BICOLORABLE.");
            else puts("NOT BICOLORABLE.");
        }
    }
}