#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

#if DEBUG
#define SIZE 4
#else
#define SIZE 212345
#endif
int N,M,Q;
vector<set<int>> E(SIZE);
int L[SIZE];
int R[SIZE];
int id = 0;

template<typename T> class ST {
    using F = function<T(T, T)>;
    int size;
    T init;
    F f;
    vector<T> seg;
    int depth = 0;
    
public: ST(int size, T init, F f): size(size), init(init), f(f) {
    while (1<<depth < size) depth++;
    seg.assign(2<<depth, init);
}
    
    void update(int k, T t) {
        k += 1 << depth;
        seg[k] = t;
        while(k>>=1) seg[k] = f(seg[2*k], seg[2*k+1]);
    }
    
    T query(int a, int b) {
        a += 1<<depth;
        b += 1<<depth;
        T l = init;
        T r = init;
        while(a < b) {
            if (a & 1) l = f(l, seg[a++]);
            if (b & 1) r = f(r, seg[--b]);
            a >>= 1;
            b >>= 1;
        }
        return f(l, r);
    }
    
    T operator[] (int k) {
        return seg[k + (1<<depth)];
    }
};


void dfs(int parent=-1, int i=0, int weight=0, int depth=0) {
    L[i] = id++;
    for (auto e : E[i]) {
        if (e == parent) continue;
        dfs(i, e);
    }
    R[i] = id++;
}


void solve() {
    cin>>N;
    int a;
    FOR(i,1,N) {
        cin>>a;
        E[i].insert(a);
        E[a].insert(i);
    }
    dfs();
    int ans = 0;
    auto s = new ST<int>(2*N+1, 0, [](int a, int b){return a+b;});
    RREP(i,N) {
        ans += s->query(L[i], R[i]);
        s->update(L[i], 1);
    }
    
    cout << ans << endl;
}