#include<bits/stdc++.h>
using namespace std;
//#include<atcoder/all>
//using namespace atcoder;
using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
constexpr ll MAX = 2000000000000000000;
constexpr ld PI = 3.14159265358979;
constexpr ll MOD = 998244353;//2024948111;
ld dotorad(ld K){return PI * K / 180.0;}
ld radtodo(ld K){return K * 180.0 / PI;}
mt19937 mt;
void randinit(){srand((unsigned)time(NULL));mt = mt19937(rand());}
int main(){
    ll N;
    cin >> N;
    vector<ll> R(N - 1);
    for(ll i = 0;i < N - 1;i++) cin >> R[i];
    ll r = 0,rr = 0,d = 0;
    while(rr != N - 1){
        ll rrr = 0;
        while(r <= rr){
            rrr = max(rrr,R[r] - 1);
            r++;
        }
        rr = rrr;
        d++;
    }
    cout << d << endl;
}