#include <bits/stdc++.h>
#define int long long
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N = 5e3+5;
int bit[N][2], inv[N][N];
void update(int idx, int pos, int val){
while(pos < N){
bit[pos][idx] += val;
pos += pos&-pos;
}
}
int query(int idx, int pos){
int res = 0;
while(pos){
res += bit[pos][idx];
pos -= pos&-pos;
}
return res;
}
signed main(){
fastio
int n;
cin >> n;
int pos[n+1] = {};
for(int i = 1;i <= n;i++){
int x;
cin >> x;
pos[x] = i;
}
int arr[n+1];
iota(arr,arr+n+1,0);
for(int i = 1;i <= n;i++){
arr[i] = pos[arr[i]];
}
for(int i = 1;i <= n;i++){
for(int j = 0;j <= n;j++){
bit[j][0] = 0;
}
for(int j = i;j <= n;j++){
inv[i][j] = inv[i][j-1] + query(0,arr[j]) + query(1,N-1) - query(1,arr[j]);
update(0,arr[j],1);
}
update(1,arr[i],1);
}
int dp[n+1] = {};
fill(dp+1,dp+n+1,1e18);
for(int i = 1;i <= n;i++){
for(int j = 0;j < i;j++){
dp[i] = min(dp[i],dp[j] + inv[j+1][i]);
//inv => inversions after reverse
}
}
cout << dp[n] << "\n";
}
