#include <bits/stdc++.h>
using namespace std;
int n, tar, a, root;
vector<int> adj[51];
 
int dfs(int here){
    if(adj[here].size() == 0) return 1;
    int cnt = 0;
    for(int i = 0; i < adj[here].size(); i++){
        int there = adj[here][i];
        if(there == tar) continue;
        cnt += dfs(there);
    }
    return cnt;
}
 
int main(){
    cin >> n;
    for(int i = 0; i < n; i++){
        cin >> a;
        if(a == -1) root = i;
        else adj[a].push_back(i);
    }
    cin >> tar;
 
    cout << dfs(root) << '\n';
}

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OQotMSAwIDAgMiAyIDQgNCA2IDYKNA==

9
-1 0 0 2 2 4 4 6 6
4