#include <iostream>
#include <math.h>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
#include <stack>
#include <map>
#include <cstring>
#include <iomanip>
#include <set>
#include <bitset>
#include <bit>
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using piii = tuple<int,int,int>;
#define endl '\n'
#define f first
#define s second
int const N = 5e3+10;
int INF = 1e9+10;
int dp[N];
int vc[N];
int fenwick[8*N];
int si;
void update(int n, int val){
for(;n <= si;n += n&-n) fenwick[n] += val;
}
int sum(int n){
int ans = 0;
for(;n > 0;n -= n&-n) ans += fenwick[n];
return ans;
}
int main(){
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n;cin >> n;
si = pow(2,ceil(log2(n)));
for(int i{};i < n;i++){
cin >> vc[i];
}
dp[2] = 0;
for(int t{3};t <= n;t++){
dp[t] = INF;
vector<pii> pos(t+1);
int i = 0;
for(int j{};j < n;j++){
if(vc[j] <= t){
pos[vc[j]] = {j,i};
i++;
}
}
for(int i{t};i >= 1;i--){
int cnt = 0;
memset(fenwick,0,sizeof fenwick);
for(int j{i};j <= t;j++){
int val = t-pos[j].s;
cnt += val-1;
cnt -= sum(val);
update(val,1);
}
dp[t] = min(dp[t],dp[i-1]+cnt);
}
}
cout << dp[n];
}
