8670번: Przegrody ↗

#include <bits/stdc++.h>

#define for1(s,n) for(int i = s; i < n; i++)
#define for1j(s,n) for(int j = s; j < n; j++)
#define foreach(k) for(auto i : k)
#define foreachj(k) for(auto j : k)
#define pb(a) push_back(a)
#define sz(a) a.size()

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef vector <int> iv1;
typedef vector <vector<int> > iv2;
typedef vector <ll> llv1;
typedef unsigned int uint;
typedef vector <ull> ullv1;
typedef vector <vector <ull> > ullv2;

bool check[1100000];
ll ans, mx;
ll N, num;

int main() {
  ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);

	cin >> N;
	
	ll crt = 1;

	for1(0, N) {
		
		cin >> num;
		
		check[num] = true;
		mx = max(num, mx);

		if(crt == num) {
			while(check[crt]) {
				crt++;
			}

			if(mx == crt - 1) {
				ans++;
			}	
		}
	}
	
	cout << ans;
}