#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using namespace std;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll mod=1000000007;
ll inf=1000;
int main(){
    ll n;
    cin >> n;
    vector<ll>r(n-1);
    for (ll i = 0; i < n-1; i++)
    {
        cin >> r[i];
        r[i]--;
    }
    ll now=0;
    ll x=0;
    ll nex=0;
    for (ll i = 0; i < n; i++)
    {
        nex=max(nex,r[i]);
        if (now==i)
        {
            now=nex;
            x++;
        }
    }
    cout << x-1 << endl;
}