func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 1e5 + 100;   int sz[maxn], N, M;   int main() {     scanf( %d%d , &N, &M);     memset(sz, 0, sizeof(sz));     vector<int> cnt;     cnt.resize(N);     int a, b;     for (int i = 1; i <= M; i++) {       scanf( %d%d , &a, &b);       a--, b--;       cnt[a]++, cnt[b]++;     }     sort(cnt.begin(), cnt.end());     for (int i = 0; i < N; i++) sz[cnt[i]]++;     if (sz[2] == N)       printf( ring topology n );     else if (sz[1] == 2 && sz[2] == N - 2)       printf( bus topology n );     else if (sz[1] == N - 1 && sz[N - 1] == 1)       printf( star topology n );     else       printf( unknown topology n );   }   