#include <iostream>
using namespace std;
const int N = 5005;
int dp[N], inv[N][N], ext[N][N], ind[N], ft[2][N];
void Add(int t, int i){
for (; i; i -= i & -i)
ft[t][i]++;
}
int get(int t, int i, int ans = 0){
for (; i < N; i += i & -i)
ans += ft[t][i];
return ans;
}
int main(){
int n;
cin>>n;
for (int i=1, a;i<=n;i++)
cin>>a, ind[a] = i, dp[i] = 1e9;
for (int l=1;l<=n;l++){
for (int i=1;i<N;i++)
ft[0][i] = 0;
for (int r=l;r<=n;r++){
inv[l][r] = inv[l][r-1] + get(0, n - ind[r] + 1);
ext[l][r] = ext[l][r-1] + get(1, ind[r]);
Add(0, n - ind[r] + 1);
}
Add(1, ind[l]);
}
for (int i=0;i<n;i++){
for (int j=i+1;j<=n;j++)
dp[j] = min(dp[j], dp[i] + inv[i+1][j] + ext[i+1][j]);
}
cout<<dp[n]<<'\n';
}
