void bfs(int s, vector<int> adj[], bool vis[], int N)
{

    queue<int> q;
    q.push(s);
    while(!q.empty()){
        int top =q.front();
        for (auto x : adj[top])
            if (!vis[x])
                q.push(x);
        cout << top << ' ';
        vis[top] = true;
        q.pop();
    }
    cout << endl;


}