邻接表

#include<bits/stdc++.h>
using namespace std;
vector<int> ve[10005];
int main(){
    int m; cin >> m;
    for(int i = 1;i <= m;i++){
        int u,v; cin >> u >> v;
        ve[u].push_back(v);
        ve[v].push_back(u);
    }
    int p; cin >> p;
    cout << ve[p].size() << endl;
    for(int i = 0;i < ve[p].size();i++){
        cout << ve[p][i] << " ";
    }
    return 0;
}