#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#include <iostream>
using namespace std;
#define INF 0x7f7f7f7f
int h[5005], pos[5005], mn[5005];
int psum[5005][5005], dp[5005][5005];
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
for(int i = 1; i <= n; i++)
{
cin >> h[i];
pos[h[i]] = i;
}
for(int i = 1; i <= n; i++)
{
for(int j = i+1; j <= n; j++)
if(h[i] > h[j])
psum[h[i]][h[j]] = 1;
for(int j = 2; j <= h[i]; j++)
psum[h[i]][j] += psum[h[i]][j-1];
}
fill(mn+1, mn+n+1, INF);
for(int it = 1; it <= n; it++)
{
dp[it][it] = mn[it-1];
for(int x = it; x <= n; x++)
{
int xpos = pos[x] + psum[x][it-1];
dp[it][x] += (dp[it][x-1] + (xpos-it) - (psum[x][x]-psum[x][it-1]));
mn[x] = min(mn[x], dp[it][x]);
}
}
cout << mn[n] << '\n';
}
