#include <bits/stdc++.h>
using namespace std;
const int mx = 1e5 + 1;
bool vis[mx];
vector<int> adj[mx];
int n;
bool star() {
  bool ans;
  int count1 = 0;
  int other = 0;
  for (int i = 1; i <= n; i++) {
    if (adj[i].size() == 1) {
      count1++;
    } else if (adj[i].size() == n - 1) {
      other++;
    }
  }
  if (other == 1 && count1 == n - 1) {
    ans = true;
  } else {
    ans = false;
  }
  return ans;
}
bool ring() {
  bool ans = true;
  for (int i = 1; i <= n; i++) {
    if (adj[i].size() != 2) {
      ans = false;
      break;
    }
  }
  return ans;
}
bool bus() {
  bool ans;
  int one = 0;
  int two = 0;
  for (int i = 1; i <= n; i++) {
    if (adj[i].size() == 1) {
      one++;
    } else if (adj[i].size() == 2) {
      two++;
    }
  }
  if (one == 2 && two == n - 2) {
    ans = true;
  } else {
    ans = false;
  }
  return ans;
}
int main() {
  int m, k, u, v;
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    cin >> u >> v;
    adj[u].push_back(v);
    adj[v].push_back(u);
  }
  if (star()) {
    cout << "star topology" << endl;
  } else if (bus()) {
    cout << "bus topology" << endl;
  } else if (ring()) {
    cout << "ring topology" << endl;
  } else {
    cout << "unknown topology" << endl;
  }
}
