/**
____ ____ ____ ____ ____ ____
||l |||e |||i |||n |||a |||d ||
||__|||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|/__\|
**/
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
typedef long long ll;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
const int maxn = 5010;
int n, a[maxn], dp[maxn], pos[maxn], cnt[maxn][maxn], par[maxn][maxn];
void solve()
{
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 ++)
{
cnt[i][j] = cnt[i - 1][j] + cnt[i][j - 1] - cnt[i - 1][j - 1];
if (pos[i] == j)
cnt[i][j] ++;
}
for (int i = 1; i <= n; i ++)
for (int j = 1; j <= n; j ++)
par[i][j] = par[i][j - 1] + cnt[i][pos[j]];
/**for (int i = 1; i <= n; i ++, cout << endl)
for (int j = 1; j <= n; j ++)
cout << cnt[i][j] << " ";*/
for (int i = 1; i <= n; i ++)
{
dp[i] = n * n;
int all = 0;
for (int k = i; k > 0; k --)
all += (cnt[n][pos[k]] - cnt[i][pos[k]]) + cnt[k - 1][pos[k]];
for (int j = 0; j < i; j ++)
{
if (j > 0)
all -= ((cnt[n][pos[j]] - cnt[i][pos[j]]) + cnt[j - 1][pos[j]]);
int sum = - (par[j][i] - par[j][j]);
/**for (int k = i; k > j; k --)
{
///ll cur = pos[k] + (j + (i - k) - query(pos[k] - 1));
ll cur = - cnt[j][pos[k]];
///cout << i << " : " << j << " : " << k << " " << cnt[n][pos[k]] << " " << cnt[k][pos[k]] << endl;
//cur -= st;
//st ++;
sum = sum + cur;
}*/
///cout << i << " " << j << " " << sum << endl;
dp[i] = min(dp[i], dp[j] + sum + all);
}
///cout << i << " -- " << dp[i] << endl;
}
cout << dp[n] << endl;
}
int main()
{
solve();
return 0;
}
