#include <bits/stdc++.h>
#define int long long
using namespace std;
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int n;
cin>>n;
int a[n];
vector<bool> b(n);
fill(b.begin(),b.end(),false);
int yukseklik=-1;
int idx=-1;
int cnt=0;
for(int i=0;i<n;i++)cin>>a[i];
while(find(b.begin(),b.end(),false)!=b.end()){
for(int i=0;i<n;i++){
if(b[i]==false){
idx=i;
yukseklik=a[i];
cnt++;
break;
}
}
for(int i=idx;i<n;i++){
if(a[i]==yukseklik){
b[i]=true;
yukseklik--;
}
}
}
cout<<cnt;
return 0;
}
