#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define REP(i, n) for(int i=0; i<n; i++)
#define REPi(i, a, b) for(int i=int(a); i<int(b); i++)
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll MOD = 1e9+7;

class SegmentTree{
    int n;
    vector<int> node;

    public:
    SegmentTree(vector<int> v){
        n = 1;
        while(v.size() > n) n *= 2;
        node.resize(2*n-1);

        for(int i = 0; i < v.size(); i++)
            node[i+n-1] = v[i];
        for(int i = n-1; i >= 0; i--)
            node[i] = node[2*i+1] + node[2*i+2];
    }

    void add(int x, int t){
        x += n-1;
        node[x] += t;
        while(x > 0){
            x = (x-1) / 2;
            node[x] = node[2*x+1] + node[2*x+2];
        }
    }

    int getsum(int a, int b, int k=0, int l=0, int r=-1){
        if(r < 0) r = n;

        if(b <= l || r <= a)
            return 0;
        if(a <= l && r <= b)
            return node[k];

        int rv = getsum(a, b, 2*k+1, l, (r+l)/2);
        int lv = getsum(a, b, 2*k+2, (r+l)/2, r);
        return rv+lv;
    }
};

vector<int> G[200100];
ll ans;

void dfs(int v, SegmentTree& tree){
    ans += tree.getsum(0, v);
    for(auto&& next : G[v]){
        tree.add(next, 1);
        dfs(next, tree);
        tree.add(next, -1);
    }
}

int main(){
    int N;
    cin >> N;
    REP(i,N-1){
        int a;
        cin >> a;
        G[a].push_back(i+1);
    }

    vector<int> A(200100);
    SegmentTree tree(A);
    tree.add(0, 1);
    dfs(0, tree);

    cout << ans << endl;
    return 0;
}