#include <iostream>
#include <queue>
#include<vector>
#include<set>
#include<stack>
#include<array>
#include<string>
#include <cassert>
#include <algorithm>
using namespace std;
#define ll long long 
#define endl "\n"
void solved(){
     int n;
     cin>>n;
     vector<int> a(n+1);
     for(int i=1;i<=n-1;i++) cin>>a[i];
     multiset<int> s;
     int l=a[1];
     s.insert(a[1]);
     int ans=1;
     for(int i=2;i<=n-1;i++){
        s.insert(a[i]);
        if(s.size()==l){
           ans++;
           l=*s.rbegin();
        }
     }
     cout<<ans<<endl;
   

}
signed main(){
   
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    solved();
}