#include <bits/stdc++.h>
using namespace std;

int main()
{
    int N;
    cin >> N;
    vector<int> R(N);
    for (int i = 1; i <= N - 1; ++i)
        cin >> R[i], R[i] = max(R[i], R[i - 1]);
    int c = 1;
    int a = 0;
    while (c != N)
    {
        c = R[c];
        ++a;
    }
    cout << a << endl;
}