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

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OQotMSAwIDAgMiAyIDQgNCA2IDYKNA==

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