#include <bits/stdc++.h>
using namespace std ;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds ;
template<class T> using ordered_set = tree<T , null_type , less<T> , rb_tree_tag , tree_order_statistics_node_update> ;
const int MAX = 5000 + 10 ;
int arr[MAX] ;
int n ;
int pos[MAX] , cnt[MAX] , cnt2[MAX][MAX] ;
int dp[MAX] ;
int main()
{
ios_base::sync_with_stdio(0) ;
cin.tie(0) ;
cin>>n ;
for(int i = 1 ; i <= n ; ++i)
cin>>arr[i] ;
ordered_set<int>s ;
for(int i = 1 ; i <= n ; ++i)
{
pos[arr[i]] = i ;
cnt[i] = s.size() - s.order_of_key(arr[i]) ;
s.insert(arr[i]) ;
}
for(int i = 1 ; i <= n ; ++i)
{
for(int j = i-1 ; j >= 1 ; --j)
cnt2[i][j] = cnt2[i][j+1] + (pos[j] < pos[i]) ;
}
for(int i = n ; i >= 1 ; --i)
{
dp[i] = 1e9 ;
int inv = 0 ;
for(int j = i ; j <= n ; ++j)
{
inv += cnt[j] ;
inv += cnt2[j][i] ;
inv -= (j-i) - cnt2[j][i] ;
dp[i] = min(dp[i] , dp[j+1] + inv) ;
}
}
return cout<<dp[1]<<"\n" , 0 ;
}
