#include<bits/stdc++.h> using namespace std; int n,in[1000005],sum; vector<int> p[1000005]; int main(){ // freopen("flower.in","r",stdin); // freopen("flower.out","w",stdout); cin>>n; for(int i=1;i<=n-1;i++){ int v; cin>>v; p[i+1].push_back(v); p[v].push_back(i+1); in[v]++; in[i+1]++; } for(int i=1;i<=n;i++){ if(in[i]>2) sum++; } if(sum==0){ cout<<n*1ll*(n-1)/2; return 0; } else if(sum==1){ if(n==4){ cout<<3; } else{ cout<<0; } return 0; } return 0; }