#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define pb push_back
const int MAXN = 5005;
int N, a[MAXN], pos[MAXN], DP[MAXN], pre[MAXN][MAXN];
int BIT_u[MAXN], BIT_p[MAXN];
void upd_u(int _pos)
{
for(; _pos <= N; _pos += _pos&-_pos)
BIT_u[_pos]++;
}
void upd_p(int _pos)
{
for(; _pos <= N; _pos += _pos&-_pos)
BIT_p[_pos]++;
}
int qry_u(int _pos)
{
int res = 0;
for(; _pos; _pos -= _pos&-_pos)
res += BIT_u[_pos];
return res;
}
int qry_p(int _pos)
{
int res = 0;
for(; _pos; _pos -= _pos&-_pos)
res += BIT_p[_pos];
return res;
}
int main()
{
cin >> N;
for(int i = 1; i <= N; i++)
{
cin >> a[i];
pos[a[i]] = i;
}
for(int i = 1; i <= N; i++)
{
for(int j = 1; j <= N; j++)
BIT_p[j] = 0;
pre[i][i] = qry_u(N) - qry_u(pos[i]);
upd_p(pos[i]);
for(int j = i + 1; j <= N; j++)
{
pre[i][j] = pre[i][j - 1] + qry_p(pos[j]) + qry_u(N) - qry_u(pos[j]);
upd_p(pos[j]);
}
upd_u(pos[i]);
}
DP[1] = 0;
for(int l = 2; l <= N; l++)
{
DP[l] = (1 << 30);
for(int j = l; j >= 1; j--)
DP[l] = min(DP[l], pre[j][l] + DP[j - 1]);
}
cout << DP[N] << "\n";
return 0;
}
