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

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OQotMSAwIDAgMiAyIDQgNCA2IDYKNA==

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