#include <bits/stdc++.h>
using namespace std;
const int INF = 1000 * 1000 * 1000;
vector<int> g[100100];
int deg[100100];
bool vis[100100];
void dfs(int v) {
  vis[v] = true;
  for (int to : g[v])
    if (!vis[to]) {
      dfs(to);
    }
}
int main() {
  int N, M;
  scanf("%d%d", &N, &M);
  for (int i = 0; i < (M); ++i) {
    int u, v;
    scanf("%d%d", &u, &v);
    --u;
    --v;
    g[u].push_back(v);
    g[v].push_back(u);
    ++deg[u];
    ++deg[v];
  }
  int q = 0;
  for (int i = 0; i < (N); ++i)
    if (!vis[i]) {
      dfs(i);
      ++q;
    }
  if (q > 1) {
    puts("unknown topology");
    return 0;
  }
  sort(deg, deg + N);
  if (deg[0] == 1 && deg[1] == 1) {
    bool check = true;
    for (int i = 2; i < N; ++i)
      if (deg[i] != 2) {
        check = false;
        break;
      }
    if (check) {
      puts("bus topology");
      return 0;
    }
  }
  bool check = true;
  for (int i = 0; i < (N); ++i)
    if (deg[i] != 2) {
      check = false;
      break;
    }
  if (check) {
    puts("ring topology");
    return 0;
  }
  check = true;
  if (deg[N - 1] == N - 1) {
    for (int i = 0; i < (N - 1); ++i)
      if (deg[i] != 1) {
        check = false;
        break;
      }
    if (check) {
      puts("star topology");
      return 0;
    }
  }
  puts("unknown topology");
  return 0;
}
