/*
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("O3")
#pragma GCC target ("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
*/
#include<bits/stdc++.h>
#define sz(v) (int)v.size()
#define ll long long
#define pb push_back
#define x first
#define y second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define nl "\n"
using namespace std;
const int N = (int)1e6 + 7; // make sure this is right
const int M = (int)1e3 + 7;
const int inf = (int)2e9 + 7;
const ll INF = (ll)3e18 + 7;
const ll MOD = (ll)1e9 + 7; // make sure this is right
bool bit(int x, int i) {
return x >> i & 1;
}
int sum(int x, int y) {
x += y;
if(x >= MOD) x -= MOD;
return x;
}
int n, a[N], dp[N];
int b[301][301];
void solve() {
cin >> n;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
for(int j = 1; j <= i; ++j) b[i][j] = a[j];
sort(b[i] + 1, b[i] + 1 + i);
}
for(int i = 1; i <= n; ++i) {
bool ok = 1;
dp[i] = inf;
for(int j = i; j >= 1; --j) {
if(j < i) ok &= (a[j] <= a[j + 1]);
if(!ok) break;
bool can = (a[j] >= b[j - 1][j - 1] || a[i] <= b[j - 1][1]);
for(int k = 1; k < j - 1 && !can; ++k) {
can |= (a[j] >= b[j - 1][k] && a[i] <= b[j - 1][k + 1]);
}
if(can) dp[i] = min(dp[i], dp[j - 1] + 1);
}
}
cout << dp[n];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(NULL);
int test = 1;
//cin >> test;
for(int i = 1; i <= test; ++i) {
//cout << "Case #" << i << ": ";
solve();
}
return 0;
}
