//#define local
#ifndef local
#include "shoes.h"
#endif
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;

#define ll long long
#define fi first
#define se second
#define pb push_back
#define mp make_pair

typedef pair<ll, ll> ii;
typedef pair<ii, ll> iii;
typedef pair<ii, ii> iiii;

const ll N = 3e5 + 5;

const ll oo = 1e18 + 7, mod = 1e9 + 7;

mt19937 rng(1);

ll rnd(ll l, ll r){
	ll temp = rng() % (r - l + 1);
	return abs(temp) + l;
}

ll n;
bool used[N];

set<ll> se[N << 1];

ll bit[N];

void upd(ll id, ll val){
	for(; id <= n; id += id & -id) bit[id] += val;
}

ll get(ll id){
	ll ans = 0;
	for(; id; id -= id & -id) ans += bit[id];
	return ans;
}

ll count_swaps(vector<ll> a){
	n = a.size();
	for(ll i = 1; i <= n; i++) upd(i, 1);
	for(ll i = 0; i < a.size(); i++){
		se[a[i] + n].insert(i + 1);
	}
	ll ans = 0;
	for(ll i = 1; i <= n; i++){
		if(used[i]) continue;
		ll temp = (*se[n - a[i - 1]].begin());
		//cout << i << " " << temp << "\n";
		used[temp] = used[i] = 1;
		ans += get(temp - 1) - 1;
		//cout << ans << "\n";
		if(a[i - 1] > 0) ans++;
		se[a[i - 1] + n].erase(i);
		se[n - a[i - 1]].erase(temp);
		upd(i, -1);
		upd(temp, -1);
	}
	return ans;
}

#ifdef local
void process(){
	ll n;
	vector<ll> v;
	cin >> n;
	for(ll i = 0; i < 2 * n; i++){
		ll x;
		cin >> x;
		v.pb(x);
	}
	cout << count_swaps(v);
}

signed main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	freopen("kek.inp", "r", stdin);
	freopen("kek.out", "w", stdout);
	process();
}
#endif

/usr/bin/ld: /tmp/cclB5qis.o: in function `main':
implementer.cpp:(.text.startup+0x283): undefined reference to `count_swaps(std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status