#include <bits/stdc++.h>
#define N 5005
using namespace std;
typedef long long ll;

int n, a[N], cnt[N][N], f[N], bit[N];

void add (int x) { while (x<=n) { bit[x]++; x+=(x&(-x)); } }
int qry (int x) { int res=0; while (x) { res+=bit[x]; x-=(x&(-x)); } return res; }

int cal (int l, int r)
{
    int len=r-l+1;
    return cnt[1][r]-cnt[1][l-1]-cnt[l][r]+(len*(len-1)/2)-cnt[l][r];
}

int main ()
{
    // freopen("0test.in", "r", stdin);
    // freopen("0test.out", "w", stdout);

    scanf("%d", &n);
    for (int i=1; i<=n; i++) { scanf("%d", &a[i]); }

    for (int l=1; l<=n; l++) {
        fill(bit+1, bit+n+1, 0);
        for (int r=l; r<=n; r++) {
            add(a[r]);
            cnt[l][r]=cnt[l][r-1]+r-l+1-qry(a[r]);
        }
    }
    
    for (int i=1; i<=n; i++) {
        f[i]=i*(i-1)/2;
        for (int j=i; j>=1; j--) {
            f[i]=min(f[i], f[j-1]+cal(j, i));
        }
    }
    printf("%d\n", f[n]);

    return 0;
}