Revise paste f7956e3eb5147

#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vll = vector<ll>;
using pll = pair<ll, ll>;
using mll = map<ll,ll>;
using sll = set<ll>;
#define iv(v) for(auto &i:v) cin >> i
#define ov(v) for(auto &i:v) cout << i << " "
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define YES cout << "YES\n"
#define NO  cout << "NO\n"

#define Bismillah ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);

const ll MOD = 1e9 + 7;

ll add(ll a, ll b) {return ((a % MOD) + (b % MOD)) % MOD;}
ll mul(ll a, ll b) {return ((a % MOD) * (b % MOD)) % MOD;}
ll sub(ll a, ll b) {return (((a - b) % MOD) + MOD) % MOD;}
ll modExp(ll a, ll b) {
    if (b <= 0) return 1;
    ll ret = modExp(a * a % MOD, b / 2);
    if (b % 2) ret = ret * a % MOD;
    return ret;
}
ll inverse(ll b) {return modExp(b, MOD - 2);}
ll divv(ll a, ll b) {return ((a % MOD) * (inverse(b) % MOD)) % MOD;}

/////////////////////////////////////////////////////////////////////////////////////////////////////////////

ll n;
vector<vll>adj(n);

void dfs(ll v, ll p) {

}
void solve() {
    int m;
    cin >> n >> m;
    mll f;
    for (int i=0; i<m; i++) {
        ll u,v; cin >> u >> v; u--; v--;
//        adj[u].push_back(v);
//        adj[v].push_back(u);
        f[u]++; f[v]++;
    }
    if (n==m) {
        for (int i=0; i<n; i++) {
            if (f[i]!=2) goto a;
        }
        cout << "ring topology" << endl; return;
    }
    a:
    if (n==m+1) {
        ll g=1;
        for (int i=0;i<n; i++) {
            if (f[i]!=1) {
                if (g&&f[i]==m) g--;
                else goto b;
            }
        }
            cout << "star topology" << endl; return;
        b:
        g=2;
        for (int i=0;i<n; i++) {
            if (f[i]!=2) {
                if (g&&f[i]==1) g--;
                else goto b;
            }
        }
            cout << "bus topology" << endl; return;

}
    cout << "unknown topology" << endl;
}

int main() {
    Bismillah
    ll t=1;
//    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}