#include <bits/stdc++.h>
#define uwu return 0;
using namespace std;
#define int _int
using _int = long long;
const int SIZE = 5e3 + 5, INF = 1e9 + 7;
int dp[SIZE];
struct BITree{
int BIT[SIZE];
void init(){
for (int i = 0; i < SIZE;i++){
BIT[i] = 0;
}
return;
}
void modify(int pos, int val){
for (; pos < SIZE;pos += (pos & -pos)){
BIT[pos] += val;
}
return;
}
int query(int pos){
int ret = 0;
for (; pos; pos -= (pos & -pos)){
ret += BIT[pos];
}
return ret;
}
}lss_amnt, grt_amnt;
int N;
int pos[SIZE];
signed main(){
cin >> N;
int in_i;
for (int i = 1; i <= N;i++){
cin >> in_i;
pos[in_i] = i;
}
int shift;
//dp[i] = with i ~ i inserted, the minimum numbers of switch needed
for (int i = 1; i <= N;i++){
shift = 0;
dp[i] = INF;
grt_amnt.init();
lss_amnt.modify(pos[i], 1);
//from j to i is the last decreasing
for (int j = i; j >= 1;j--){
shift += i - lss_amnt.query(pos[j]) - grt_amnt.query(pos[j]);
dp[i] = min(dp[i], dp[j - 1] + shift);
grt_amnt.modify(pos[j], 1);
}
}
cout << dp[N] << '\n';
}
