#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 5010;
int fenp[N], fenn[N];
void add(int i, int x, int fen[])
{
++i;
while (i < N) {
fen[i] += x;
i += i & -i;
}
}
int get(int r, int fen[])
{
int ans = 0;
while (r > 0) {
ans += fen[r];
r -= r & -r;
}
return ans;
}
int dp[N];
int pos[N];
int n;
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n;
Loop (i,0,n) {
int h;
cin >> h;
pos[h-1] = i;
}
dp[n] = 0;
LoopR (i,0,n) {
memset(fenn, 0, sizeof(fenn));
add(pos[i], 1, fenp);
int sum = 0;
dp[i] = 1e9;
Loop (j,i,n) {
sum += get(pos[j], fenp) + get(n-pos[j], fenn);
add(n-pos[j], -1, fenn);
dp[i] = min(dp[i], dp[j+1] + sum);
}
}
cout << dp[0] << '\n';
}
