#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<long long, long long>
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define endl '\n'
#define ld long double
#define sz(x) static_cast<int>((x).size())
#define i5 tuple<int,int,int,int,int>
#define all(x) x.begin(), x.end()
#define iiii tuple<int, int,int,int>
#define ld long double
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
const int maxn=5005;
int fw[3][maxn];
void upd(int t, int x, int v){
while(x <= maxn){
fw[t][x]+=v;
x+=(x&(-x));
}
}
int qry(int t, int x){
int ret=0;
while(x > 0){
ret += fw[t][x];
x-=(x&(-x));
}
return ret;
}
signed main(){
int n;cin>>n;
vector<int> v(n+1), pos(n+1); for(int i=1;i<=n;i++){
cin>>v[i];
pos[v[i]]=i;
}
vector<vector<int>> cost(n+1, vector<int>(n+1, 0));
for(int i=1;i<=n;i++){
upd(1, i, 1);
}
/*cout<<pos[1]<<endl;
cout<<qry(1, pos[1]-1);
return 0;*/
vector<int> rb;
for(int j=1;j<=n;j++){
for(auto it: rb){
upd(2, it, -1);
}
rb.clear();
int cc=0;
for(int i=j;i<=n;i++){
int minus=qry(2, maxn) - qry(2, pos[i]);
int mv=qry(1, pos[i]-1);
cc += mv - minus;
upd(2, pos[i], 1);
rb.pb(pos[i]);
cost[j][i] = cc;
//printf("cost of %lld to %lld is %lld,mv %lld minused %lld\n", j, i, cc, mv, minus);
}
upd(1, pos[j], -1);
//if(j==1)break;
}
vector<int> dp(n+1, 1e9);
dp[0]=0;
for(int i=1;i<=n;i++){
for(int j=1;j<=i;j++){
dp[i]=min(dp[i], dp[j-1] + cost[j][i]);
}
}
cout<<dp[n];
}
