#include <bits/stdc++.h>
using namespace std;
int inf = 1e9;
int n,a[5005],pos[5005];
int dp[5005],cost[5005][5005];
int v[5005],sp[5005];
int aib[5005];
void update(int pos,int val)
{
for (int i = pos; i <= n; i += (i & -i))
aib[i] += val;
}
int query(int pos)
{
int r = 0;
for (int i = pos; i > 0; i -= (i & -i))
r += aib[i];
return r;
}
void prec_cost()
{
for (int j = 1; j <= n; j++)
{
///aici calculez cost[i][j]
for (int i = 1; i <= n; i++)
aib[i] = 0,v[i] = 0;
for (int i = 1; i <= n; i++)
if (a[i] > j)
v[i] = 1;
for (int i = 1; i <= n; i++)
sp[i] = sp[i - 1] + v[i];
int cst = 0;
for (int i = j; i >= 1; i--)
{
///in primul rand cate neinversiuni sunt intre astea <=> (j - i) - cate de pana acum sunt pe poz mai mici
cst += (j - i) - query(pos[i] - 1);
///in al doilea rand cate mai mari ca j sunt in spate
cst += sp[pos[i] - 1];
cost[i][j] = cst;
update(pos[i],1);
}
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin >> n;
for (int i = 1; i <= n; i++)
cin >> a[i],pos[a[i]] = i;
prec_cost();
dp[0] = 0;
for (int i = 1; i <= n; i++)
{
dp[i] = inf;
for (int j = 0; j < i; j++)
dp[i] = min(dp[i],dp[j] + cost[j + 1][i]);
}
cout << dp[n];
return 0;
}
