#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<int> hs(n + 1);
vector<int> a(n);
for(int i = 0;i < n;i++){
int x;
cin >> x;
a[i] = x;
hs[x] = i + 1;
}
vector<vector<int>> f(n + 1,vector<int>(n + 1));
for(int i = 1;i <= n;i++){
vector<int> ta(n,-1);
int cnt = 0;
for(int j = n - 1;j >= 0;j--){
if(a[j] <= i - 1){
cnt ++;
}else{
assert(ta[j + cnt] == -1);
ta[j + cnt] = a[j];
}
}
vector<int> nhs(n + 1);
for(int i = 0;i < n;i++){
if(ta[i] != -1) nhs[ta[i]] = i + 1;
}
for(int j = i;j <= n;j++){
int wh = nhs[j];
int ex = 0;
for(int k = nhs[j] + 1;k <= n;k++){
if(ta[k - 1] != -1 && ta[k - 1] >= i && ta[k - 1] <= j - 1) ex ++;
}
f[i][j] = -ex + wh - i;
}
}
const i64 inf = 1e18;
vector<i64> dp(n + 2,inf);
dp[n + 1] = 0;
for(int i = n;i >= 1;i--){
i64 tot = 0;
for(int j = i;j <= n;j++){
tot += f[i][j];
dp[i] = min(dp[j + 1] + tot,dp[i]);
}
}
cout << dp[1] << '\n';
return 0;
}
