#include <bits/stdc++.h>
using namespace std;
#ifdef ngu
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = 5005;
int n;
int h[N];
int pos[N];
int t[N];
int dp[N];
int cnt[N][N];
int cost[N][N];
int get(int l, int r) {
return l <= r ? t[r] - t[l - 1] : 0;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
#ifdef ngu
freopen("test.inp", "r", stdin);
freopen("test.out", "w", stdout);
#endif
cin >> n;
for (int i = 1; i <= n; ++i) {
cin >> h[i];
pos[h[i]] = i;
}
for (int l = n; l >= 1; --l) {
for (int r = l + 1; r <= n; ++r) {
cnt[l][r] = cnt[l + 1][r] + cnt[l][r - 1] - cnt[l + 1][r - 1] + (pos[l] < pos[r]);
}
}
for (int r = 1; r <= n; ++r) {
fill(t + 1, t + n + 1, 0);
for (int i = r + 1; i <= n; ++i) {
t[pos[i]]++;
}
for (int i = 1; i <= n; ++i) {
t[i] += t[i - 1];
}
for (int l = r; l >= 1; --l) {
cost[l][r] = get(1, pos[l] - 1);
cost[l][r] += cost[l + 1][r];
}
for (int l = 1; l <= r; ++l) {
cost[l][r] += cnt[l][r];
}
}
for (int i = 1; i <= n; ++i) {
dp[i] = 1e9;
for (int j = 0; j < i; ++j) {
dp[i] = min(dp[i], dp[j] + cost[j + 1][i]);
}
}
cout << dp[n];
}
