using namespace std;
const int N = 10010;
int h[N], e[N], ne[N], idx;
bool flag[N];
int add(int a,int b) {
    e[idx] = b;
    ne[idx] = h[a];
    h[a] = idx++;
}
int dfs(int u)
{
    flag[u] = true;
    for (int i = h[u]; i != -1; i = ne[i])
    {
        int j = e[i];
        if (!flag[j])
        {
            dfs(j);
        }
    }
}

int bfs(int st)
{
    queue<int> Q;
    Q.push(st);
    flag[st] = true;
    while (Q.size())
    {
        int fr = Q.front();
            Q.pop();
            for (int i = h[fr]; i != -1; i = ne[i])
            {
                int j = e[i];
                if (!flag[j])
                {
                    flag[j] = true;
                    Q.push(j);
                }

            }
    }
}