//歡迎指正！！！//


//有向圖找環
//輸入n條邊
const int maxvex = 500;
int graph[maxvex][maxvex] = {0};//鄰接矩陣
set<int>vexs;//頂點容器
bool visitted[maxvex] = {false};//訪問陣列
vector<vector<int>>ans;//路徑容器

void CreatGraph() {
    int eages = 0;
    cin >> eages;
    int first, second;
    for (int i = 0; i < eages; ++i) {
        cin 
 
>> first >> second;
        graph[first][second] = 1;
        vexs.insert(first);
    }
}
void Dfs(int x, int& count, queue<int> routes) {

    if (visitted[x]) {//存在環
        count++;
        queue<int>routes1(routes);
        vector<int>temp;
        while (routes1.front() != x) {
            routes1.pop();
        }
        
 
while (!routes1.empty()) {
            temp.push_back(routes1.front());
            routes1.pop();
        }
        ans.push_back(temp);
    }
    else {
        visitted[x] = true;
        routes.push(x);
        set<int>::iterator it;
        for (it = vexs.begin(); it != vexs.end(); ++it) {
            
 
if (graph[x][(*it)]) {
                Dfs((*it), count, routes);
            }
        }
    }
}
void CheckCircle() {
    int count = 0;//環的數量
    queue<int>routes;//儲存可能的環
    set<int>::iterator it;
    for (it = vexs.begin(); it!=vexs.end(); ++it) {
        if (!visitted[(*it)]) {
            Dfs((*it), count, routes);
        }
    }
}