#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define pb push_back
#define popf pop_front
#define popb pop_back
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if (str != "") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 5005;
// bit
struct fenwick {
int size;
vector<long long> tree;
void init(int size_) {
tree.assign(size_ + 2, 0);
size = size_;
}
void upd(int u, long long v) {
while(u <= size) {
tree[u] += v;
u += u & (-u);
}
}
long long qry(int u) {
long long sum = 0;
while(u > 0) {
sum += tree[u];
u -= u & (-u); // lsb
}
return sum;
}
long long sum(int l, int r) {
return qry(r) - qry(l - 1);
}
};
int n, pos[N];
int get(vector<int>& a, vector<int>& b) {
fenwick ft;
ft.init(n + 1);
int ans = 0;
for(int i = 0; i < n; i++) {
int wh = pos[b[i]];
ans += wh - 1 - ft.qry(wh);
ft.upd(wh, 1);
}
return ans;
}
int dp[N];
int rec(int to) {
if(to == 0) {
return 0;
}
if(dp[to] != -1) {
return dp[to];
}
int maxi = n - (n - to);
fenwick ft;
ft.init(n + 1);
for(int i = maxi + 1; i <= n; i++) {
ft.upd(pos[i], 1);
}
int put = n * n;
for(int i = to; i >= 1; i--) {
fenwick nft = ft;
int nd = to - i;
int cur = maxi - nd, sm = 0;
for(int j = to; j >= i; j--, cur++) {
int suf = n - pos[cur];
suf -= nft.sum(pos[cur], n);
nft.upd(pos[cur], 1);
sm += suf;
}
put = min(put, sm + rec(i - 1));
}
dp[to] = put;
return dp[to];
}
void solve_() {
cin >> n;
vector<int> a(n);
for(int i = 0; i < n; i++) {
cin >> a[i];
pos[a[i]] = i + 1;
}
// int ans = n * n;
// for(int i = 1; i < (1 << n); i++) {
// if(!(i & 1)) continue;
// vector<int> b(n);
// int it = n, lst = n - 1;
// for(int j = n - 1; j >= 0; j--) {
// if(i & (1 << j)) {
// b[j] = it;
// it -= (lst - j + 1);
// lst = j - 1;
// }
// }
// for(int j = 0; j < n; j++) {
// if(b[j]) continue;
// b[j] = b[j - 1] - 1;
// }
// ans = min(ans, get(a, b));
// }
for(int i = 0; i <= n; i++) {
dp[i] = -1;
}
cout << rec(n) << '\n';
}
int main() {
setIO();
auto solve = [&](int test_case)-> void {
while(test_case--) {
solve_();
}
};
int test_cases = 1;
// cin >> test_cases;
solve(test_cases);
return 0;
}
