#include <bits/stdc++.h>
using namespace std;
int n, m, in[100010], sum1, sum2;
int main() {
  cin >> n >> m;
  for (int i = 1; i <= m; i++) {
    int x, y;
    cin >> x >> y;
    in[x]++;
    in[y]++;
  }
  for (int i = 1; i <= n + 1; i++)
    if (in[i] == 1)
      sum1++;
    else if (in[i] == 2)
      sum2++;
  if (sum1 == 2 && sum2 == n - 2) {
    cout << "bus topology";
    return 0;
  }
  sum1 = sum2 = 0;
  for (int i = 1; i <= n; i++)
    if (in[i] == 2) sum1++;
  if (sum1 == n) {
    cout << "ring topology";
    return 0;
  }
  sum1 = sum2 = 0;
  for (int i = 1; i <= n + 1; i++)
    if (in[i] == 1)
      sum1++;
    else if (in[i] == n - 1)
      sum2++;
  if (sum1 == n - 1 && sum2 == 1) {
    cout << "star topology";
    return 0;
  }
  cout << "unknown topology";
  return 0;
}
