protest

#include <fstream>
#include <vector>
#define Nmax 100001
using namespace std;
vector<int> G[Nmax];
vector<bool> scandalagiu;
vector<bool> viz;
int n,k,nr;

void df(int nod)
{
    viz[nod]=1;
    for(auto v:G[nod])
        if(!scandalagiu[v]&&!viz[v])
            df(v),++nr;
}

int main()
{
    ifstream f("protest.in");
    f>>n>>k;
    scandalagiu=vector<bool>(n+1);
    viz=vector<bool>(n+1);
    for(int i=1,sc;i<=k;++i)
        f>>sc,scandalagiu[sc]=1;
    int x,y;
    while(--n)
        f>>x>>y,G[x].push_back(y);
    f.close();
    df(1);
    ofstream g("protest.out");
    g<<nr;
    g.close();
    return 0;
}