#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:x) cout << it << " "; cout << #y << endl;
typedef pair<int,int>pii;
typedef pair<pii,pii>pi2;
int prefix[5005][5005]; //pos val
int arr[5005];
int pos[5005];
int n=0;
int query(int l, int r, int val, int val2){
if(val2<val) return 0;
if(r<l) return 0;
int hold= prefix[r][val2]-prefix[r][val-1]-prefix[l-1][val2]+prefix[l-1][val-1];
return hold;
}
int memo[5005];
int cost[5005][5005];
int dp(int index){
if(index==n+1) return 0;
if(memo[index]!=-1) return memo[index];
int ans=INT_MAX;
for(int x=index;x<=n;x++){
int add=cost[index][x];
int take=dp(x+1);
ans=min(ans,take+add);
}
return memo[index]=ans;
}
void solve(){
cin >> n;
for(int x=1;x<=n;x++){
cin >> arr[x];
prefix[x][arr[x]]=1;
pos[arr[x]]=x;
}
for(int x=1;x<=n;x++){
for(int y=1;y<=n;y++){
prefix[x][y]+=prefix[x-1][y]+prefix[x][y-1]-prefix[x-1][y-1];
}
}
for(int x=n;x>=1;x--){
int counter=0;
for(int y=x;y>=1;y--){
counter+=query(1,pos[y],x+1,n);
counter+=query(pos[y]+1,n,y+1,x);
cost[y][x]=counter;
//show3(y,y,x,x,counter,counter);
}
}
memset(memo,-1,sizeof(memo));
cout << dp(1);
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
//freopen("in.txt", "r", stdin);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
