Language: C++

ll N, M;
vector<bool> visited(50, false);
vector<vector<ll>> m(50, vector<ll>(50, 0));
vector<ll> A;
vector<ll> B;

void dfs(ll num)
{
//      cout << "DFS = " << num << endl;
        visited[num] = true;

        for (int i = 0; i < N; ++i) {

                if (m[num][i] == 1) {
                        if (visited[i] == true) continue;
                        else dfs(i);
                }
        }
}

int main()
{
        cin >> N >> M;
        for (int i = 0; i < M; ++i) {
                ll a, b; cin >> a >> b;
                A.push_back(a-1);
                B.push_back(b-1);
                m[a-1][b-1] = 1;
                m[b-1][a-1] = 1;
        }
        ll ans = 0;
        for (int i = 0; i < M; ++i) {

                for (int j = 0; j < N; ++j) visited[j] = false;

                m[A[i]][B[i]] = 0;
                m[B[i]][A[i]] = 0;

                dfs(0);

                m[A[i]][B[i]] = 1;
                m[B[i]][A[i]] = 1;

                for (int i = 0; i < N; ++i) {
                        if (visited[i] == false) {
                                ans++;
                                break;
                        }
                }

        }
        cout << ans << endl;


}


Compiler output:
a.cc:1:1: error: 'll' does not name a type
    1 | ll N, M;
      | ^~
a.cc:2:1: error: 'vector' does not name a type
    2 | vector<bool> visited(50, false);
      | ^~~~~~
a.cc:3:1: error: 'vector' does not name a type
    3 | vector<vector<ll>> m(50, vector<ll>(50, 0));
      | ^~~~~~
a.cc:4:1: error: 'vector' does not name a type
    4 | vector<ll> A;
      | ^~~~~~
a.cc:5:1: error: 'vector' does not name a type
    5 | vector<ll> B;
      | ^~~~~~
a.cc:7:6: error: variable or field 'dfs' declared void
    7 | void dfs(ll num)
      |      ^~~
a.cc:7:10: error: 'll' was not declared in this scope
    7 | void dfs(ll num)
      |          ^~
a.cc: In function 'int main()':
a.cc:23:9: error: 'cin' was not declared in this scope
   23 |         cin >> N >> M;
      |         ^~~
a.cc:23:16: error: 'N' was not declared in this scope
   23 |         cin >> N >> M;
      |                ^
a.cc:23:21: error: 'M' was not declared in this scope
   23 |         cin >> N >> M;
      |                     ^
a.cc:25:17: error: 'll' was not declared in this scope
   25 |                 ll a, b; cin >> a >> b;
      |                 ^~
a.cc:25:33: error: 'a' was not declared in this scope
   25 |                 ll a, b; cin >> a >> b;
      |                                 ^
a.cc:25:38: error: 'b' was not declared in this scope
   25 |                 ll a, b; cin >> a >> b;
      |                                      ^
a.cc:26:17: error: 'A' was not declared in this scope
   26 |                 A.push_back(a-1);
      |                 ^
a.cc:27:17: error: 'B' was not declared in this scope
   27 |                 B.push_back(b-1);
      |                 ^
a.cc:28:17: error: 'm' was not declared in this scope
   28 |                 m[a-1][b-1] = 1;
      |                 ^
a.cc:31:9: error: 'll' was not declared in this scope
   31 |         ll ans = 0;
      |         ^~
a.cc:34:45: error: 'visited' was not declared in this scope
   34 |                 for (int j = 0; j < N; ++j) visited[j] = false;
      |                                             ^~~~~~~
a.cc:36:17: error: 'm' was not declared in this scope
   36 |                 m[A[i]][B[i]] = 0;
      |                 ^
a.cc:36:19: error: 'A' was not declared in this scope
   36 |                 m[A[i]][B[i]] = 0;
      |                   ^
a.cc:36:25: error: 'B' was not declared in this scope
   36 |                 m[A[i]][B[i]] = 0;
      |                         ^
a.cc:39:17: error: 'dfs' was not declared in this scope
   39 |                 dfs(0);
      |                 ^~~
a.cc:45:29: error: 'visited' was not declared in this scope
   45 |                         if (visited[i] == false) {
      |                             ^~~~~~~
a.cc:46:33: error: 'ans' was not declared in this scope
   46 |                                 ans++;
      |                                 ^~~
a.cc:52:9: error: 'cout' was not declared in this scope
   52 |         cout << ans << endl;
      |         ^~~~
a.cc:52:17: error: 'ans' was not declared in this scope
   52 |         cout << ans << endl;
      |                 ^~~
a.cc:52:24: error: 'endl' was not declared in this scope
   52 |         cout << ans << endl;
      |                        ^~~~