#include "bits/stdc++.h"
using namespace std;
#ifdef DEBUG
auto&operator<<(auto &o, pair<auto, auto> p) {o << "(" << p.first << ", " << p.second << ")"; return o;}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{"; for(auto e : x) o<<e<<", "; return o<<"}";}
#define debug(X) cerr << "["#X"]: " << X << '\n';
#else
#define cerr if(0)cout
#define debug(X) ;
#endif
using ll = long long;
#define all(v) (v).begin(), (v).end()
#define ssize(x) int(x.size())
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
const int inf = 1e9+10;
struct segtree {
int base;
vector<int> t;
segtree(int n) {
base = 1;
while (base < n) base *= 2;
t.resize(2*base);
}
void update(int v, int x) {
v += base;
while (v)
t[v] += x, v /= 2;
}
int query(int l, int r) {
l += base - 1; r += base + 1;
int res = 0;
while (l/2 != r/2) {
if (l%2 == 0) res += t[l+1];
if (r%2 == 1) res += t[r-1];
l /= 2; r /= 2;
}
return res;
}
};
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n;
cin >> n;
vector<int> h(n);
for (int &x : h) {
cin >> x;
--x;
}
vector<int> p(n);
for (int i = 0; i < n; ++i) p[h[i]] = i;
vector<int> dp(n+1, inf);
dp[n] = 0;
segtree l(n);
for (int j = n-1; j >= 0; --j) {
l.update(p[j], 1);
int pref = 0;
segtree r(n);
for (int i = j; i < n; ++i) {
int pos = p[i];
pref += l.query(0, pos-1) - r.query(pos, n-1);
r.update(pos, +1);
dp[j] = min(dp[j], pref + dp[i+1]);
}
}
cout << dp[0] << '\n';
return 0;
}
