This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
#define ff	first
#define ss	second
#define pii	pair<int, int>
#define sz(v)	(int)(v).size()
#define all(v)	(v).begin(), (v).end()
int main() {
	ios::sync_with_stdio(false); cin.tie(nullptr);
	int n;
	cin >> n;
	vector<int> a(n);
	for (auto &i : a) {
		cin >> i; i--;
	}
	int mn = INT_MAX;
	for (int mk = 0; mk < 1 << (n - 1); mk++) {
		bool tr = true;
		int pre = -1, cnt = 0;
		map<int, vector<int>> m;
		for (int i = 0; i < n && tr; i++) {
			if (i != n - 1 && !((mk >> i) & 1)) continue;
			for (int j = pre + 1; j < i && tr; j++) {
				tr = (a[j] <= a[j + 1]);
				m[a[j]].push_back(a[j + 1]);
			}
			cnt++; pre = i;
		}
		if (!tr) continue;
	
		set<int> s = {INT_MAX};
		for (auto i : m) {
			for (auto j : i.ss) {
				if (*s.upper_bound(i.ff) < j) {
					tr = false; break;
				}
			}
			if (!tr) break;
			for (auto j : i.ss)
				s.insert(j);
		}
		if (tr) mn = min(mn, cnt);
	}
	assert(mn != INT_MAX);
	cout << mn;
}
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