#include<bits/stdc++.h>
using namespace std;
const int MX = 5004;
int n;
int a[MX];
int cost[MX][MX];
int bit[MX];
void add(int id, int delta) {
for(int i=id; i<=n; i=i|(i+1)) {
bit[i] += delta;
}
}
int sum(int r) {
int ret = 0;
for(int i=r; i>=0; i=(i&(i+1))-1) {
ret += bit[i];
}
return ret;
}
int sum(int l, int r) {
return sum(r) - sum(l-1);
}
int dp[MX];
int solve(int i) {
if(i>n) return 0;
int &ret = dp[i];
if(ret!=-1) return ret;
ret = INT_MAX;
for(int j=i; j<=n; ++j) {
ret = min(ret, solve(j+1)+cost[i][j]);
}
return ret;
}
int alt[MX];
void PlayGround() {
cin>>n;
for(int i=1; i<=n; ++i) {
cin>>a[i];
alt[a[i]] = i;
}
int inv[n+1] = {};
for(int i=1; i<=n; ++i) {
for(int j=alt[i]-1; j>0; --j) if(a[j]>i) {
++inv[i];
}
}
for(int j=1; j<=n; ++j) {
memset(bit, 0, sizeof bit);
for(int i=j; i>0; --i) {
cost[i][j] = inv[i] - sum(1, alt[i]) + sum(alt[i], n);
if(i!=j) cost[i][j] += cost[i+1][j];
add(alt[i], 1);
}
}
memset(dp, -1, sizeof dp);
cout<<solve(1)<<'\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
PlayGround();
return 0;
}
