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115A.cpp
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115A.cpp
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#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define vt vector
#define ll long long
#define pb push_back
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)(x).size()
#define en '\n'
const int d4r[4] = {-1,0,1,0}; const int d4c[4] = {0,1,0,-1};
const int d8r[8] = {-1,-1,0,1,1,1,0,-1}; const int d8c[8] = {0,1,1,1,0,-1,-1,-1};
const int INF = 0x3f3f3f3f; const int mINF = 0xc0c0c0c0;
const ll LINF = 0x3f3f3f3f3f3f3f3f; const ll mLINF = 0xc0c0c0c0c0c0c0c0;
int T = 1;
int n;
int ans = 1;
int root;
vt<int> adj[2001];
vt<bool> hasParent(2001), hasChild(2001);
int bfs(int st) {
int cnt = 0;
queue<int> q;
q.push(st);
while(!q.empty()) {
int size = q.size();
for(int i=0; i<size; ++i) {
int node = q.front(); q.pop();
for(int j=0; j<sz(adj[node]); ++j) {
q.push(adj[node][j]);
}
}
cnt++;
}
return cnt;
}
void sol() {
cin >> n;
int manager;
int st = 0;
for(int i=1; i<=n; ++i) {
cin >> manager;
if(manager == -1) {
continue;
}
adj[manager].pb(i);
hasParent[i] = 1;
hasChild[manager] = 1;
}
for(int i=1; i<=n; ++i) {
if(!hasParent[i] && hasChild[i]) {
ans = max(ans, bfs(i));
}
}
cout << ans << en;
return;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
while(T--) {
sol();
}
return 0;
}