#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 5005;
int n, a[maxn], pos[maxn];
int c[maxn][maxn], d[maxn][maxn], f[maxn];
void solve() {
cin >> n;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
pos[a[i]] = i;
}
for(int i = 1; i <= n; ++i) {
for(int j = 1; j <= n; ++j) {
c[i][j] = c[i][j - 1] + (i > j and pos[i] < pos[j]);
d[i][j] = d[i][j - 1] + (i > j and pos[i] > pos[j]);
}
for(int j = 1; j <= n; ++j) {
c[i][j] += c[i - 1][j], d[i][j] += d[i - 1][j];
}
}
memset(f, 0x3f, sizeof(f));
f[0] = 0;
for(int i = 1; i <= n; ++i) {
for(int j = 1; j <= i; ++j) {
int cost = c[i][j - 1] - c[j - 1][j - 1] + d[i][i] - d[i][j - 1];
f[i] = min(f[i], cost + f[j - 1]);
}
}
cout << f[n];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
