#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb(x) push_back(x)
#define pp pop_back()
struct node {
node *left, *right;
int S, E, M, val;
node (int _s, int _e): S(_s), E(_e) {
if (S==E) {
val=0;
return;
}
M=(S+E)/2;
left=new node(S, M);
right=new node(M+1, E);
val=0;
}
void upd (int p, int v) {
if (S==E) {
val=v;
return;
}
if (p<=M) left->upd(p, v);
else right->upd(p, v);
val=left->val+right->val;
}
int qry (int l, int r) {
if (E<l || r<S) return 0;
if (l<=S && E<=r) return val;
return left->qry(l, r)+right->qry(l, r);
}
}*root, *root2;
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
cin >> n;
int h[n], dis[n+1], dp[n+1];
dp[0]=0;
for (int i=0; i<n; i++) {
cin >> h[i];
dis[h[i]]=i;
}
dis[0]=0;
root=new node(0, n-1);
for (int i=1; i<=n; i++) dp[i]=INT_MAX;
for (int i=0; i<n; i++) { //dp[i] stores the minimum value for a prefix of staircases ending at i
root2=new node(0, n-1); //we use dp[i] to induct to dp[j] where j>i
int cur=dp[i];
for (int j=i+1; j<=n; j++) {
cur+=dis[j]-root->qry(0, dis[j])-root2->qry(dis[j], n-1);
dp[j]=min(dp[j], cur);
//cout << i << " " << j << " " << root->qry(0, dis[j]) << " " << root2->qry(dis[j], n-1) << "\n";
root2->upd(dis[j], 1);
}
root->upd(dis[i+1], 1);
}
cout << dp[n] << "\n";
return 0;
}
