#include <bits/stdc++.h>
#define IO_OP std::ios::sync_with_stdio(0); std::cin.tie(0);
#define F first
#define S second
#define V vector
#define PB push_back
#define MP make_pair
#define EB emplace_back
#define ALL(v) (v).begin(), (v).end()
#define debug(x) cerr << "Line(" << __LINE__ << ") -> " << #x << " is " << x << endl
using namespace std;
typedef long long ll;
typedef pair<int, int> pi;
typedef V<int> vi;
const int INF = 1e9 + 7, N = 5005;
int a[N], p[N], dp[N], cost[N][N];
struct BIT {
int bit[N];
BIT() {
memset(bit, 0, sizeof bit);
}
void add(int pos, int val) {
for(; pos < N; pos += pos & -pos)
bit[pos] += val;
}
int qry(int pos) {
int res = 0;
for(; pos; pos -= pos & -pos)
res += bit[pos];
return res;
}
} b;
signed main()
{
IO_OP;
int n;
cin >> n;
for(int i = 1; i <= n; i++) {
cin >> a[i];
p[a[i]] = i;
}
for(int r = 1; r <= n; r++) {
vi psum(n + 1);
for(int i = 1; i <= r; i++) psum[p[i]]++;
for(int i = 1; i <= n; i++) psum[i] += psum[i - 1];
int ans = 0;
for(int l = r; l >= 1; l--) {
ans += psum[n] - psum[p[l]];
ans -= b.qry(p[l]);
cost[l][r] = ans;
b.add(p[l], 1);
}
for(int l = r; l >= 1; l--) b.add(p[l], -1);
}
dp[0] = 0;
for(int i = 1; i <= n; i++) {
dp[i] = INF;
for(int j = 1; j <= i; j++) {
dp[i] = min(dp[i], dp[j - 1] + cost[j][i]);
}
}
cout << dp[n] << endl;
}
