#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define szof(x) ((int)(x).size())
#define vi vector<int>
#define pii pair<int, int>
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
const int INF = INT_MAX;
const int LNF = INF*INF;
const int MOD = 1000000007;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
const int MAX = 5010;
int n;
int arr[MAX][MAX]; // arr[i] = arr. after sorting [1, i]
int pos[MAX][MAX];
int cost[MAX][MAX]; // cost[i][j] = cost to sort [i, j]
int dp[MAX];
int res;
inline int sum(int l, int r){
return (l + r) * (r - l + 1) / 2;
}
#define lsb(x) ((x)&(-(x)))
int BIT[MAX];
void modify(int pos, int val){
while(pos < MAX){
BIT[pos] += val;
pos += lsb(pos);
}
}
int query(int pos){
int ret = 0;
while(pos > 0){
ret += BIT[pos];
pos -= lsb(pos);
}
return ret;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n;
FOR(i, 1, n, 1){
cin>>arr[0][i];
}
FOR(i, 1, n, 1){
int ptr;
FOR(j, 1, n, 1){
arr[i][j] = arr[i-1][j];
if(arr[i][j] == i) ptr = j;
}
while(ptr > i){
swap(arr[i][ptr-1], arr[i][ptr]);
ptr--;
}
}
FOR(i, 0, n, 1){
FOR(j, 1, n, 1){
pos[i][ arr[i][j] ] = j;
}
}
FOR(l, 1, n, 1){
int dpos = 0;
int inv = 0;
FOR(r, l, n, 1){
// cost[l, r]
dpos += pos[l-1][r] - r;
inv += query(pos[l-1][r] - 1);
modify(pos[l-1][r], 1);
cost[l][r] = dpos + inv;
}
FOR(r, l, n, 1){
modify(pos[l-1][r], -1);
}
}
FOR(r, 1, n, 1){
dp[r] = LNF;
FOR(l, 1, r, 1){
dp[r] = min(dp[r], dp[l-1] + cost[l][r]);
}
}
cout<<dp[n]<<'\n';
/*
FOR(l, 1, n, 1){
cerr<<"cost["<<l<<"] : ";
FOR(r, 1, n, 1){
cerr<<cost[l][r]<<" ";
}
cerr<<endl;
}
cerr<<endl;
*/
return 0;
}
