#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
#define FORLL(i, a, b) for (ll i = a, _b = b; i <= _b; ++i)
#define FORDLL(i, a, b) for (ll i = a, _b = b; i >= _b; --i)
#define all(x) x.begin(), x.end()
#define uni(x) sort(all(x)), x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define dbg(...) debug(#__VA_ARGS__, __VA_ARGS__)
template<typename T>
void __print_one(const char *&s, const T &x)
{
while (*s == ' ') ++s;
const char *p = s;
int bal = 0;
while (*s)
{
if (*s == '(') ++bal;
else if (*s == ')') --bal;
else if (*s == ',' && bal == 0) break;
++s;
}
cerr.write(p, s - p) << " = " << x;
if (*s == ',')
{
++s;
cerr << " , ";
}
}
template<typename... Args>
void debug(const char *s, Args... args)
{
cerr << "[ ";
int dummy[] = { 0 , ( __print_one(s, args) , 0 )... };
(void)dummy;
cerr << " ]\n\n";
}
template<class X>
bool maximize(X &a, X b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
template<class X>
bool minimize(X &a, X b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
// --------------------------------------------------------------------------------------------
const int maxn = 1e5 + 3, dx[4] = {1, -1, 0, 0}, dy[4] = {0, 0, 1, -1};
int n, sl[maxn][3], lst[3];
ll res;
// --------------------------------------------------------------------------------------------
namespace sub1
{
map<vector<vector<int>>, int> D;
bool valid(int x, int y)
{
return x >= 1 && x <= n && y >= 1 && y <= 2;
}
bool check(const auto &state)
{
FOR(i, 1, n)
FOR(j, 1, 2)
if (state[i][j] != 1)
return false;
return true;
}
void solve()
{
vector<vector<int>> iState(n + 1, vector<int>(3, 0));
FOR(i, 1, n)
FOR(j, 1, 2)
iState[i][j] = sl[i][j];
D[iState] = res;
queue<vector<vector<int>>> q;
q.push(iState);
while (q.size())
{
vector<vector<int>> state = q.front(); q.pop();
if (check(state))
return void(cout << D[state]);
FOR(i, 1, n)
FOR(j, 1, 2)
{
if (state[i][j] < 1) continue;
vector<vector<int>> nState = state;
FOR(k, 0, 3)
{
int u = i + dx[k], v = j + dy[k];
if (!valid(u, v)) continue;
--nState[i][j];
++nState[u][v];
if (!D.count(nState))
{
D[nState] = D[state] + 1;
q.push(nState);
}
}
}
}
}
}
namespace AC
{
ll F(ll x)
{
return x * (x + 1) / 2;
}
ll G(int l, int r)
{
return F(r) - F(l - 1);
}
void Lap(int i, int j)
{
if (lst[j] >= i - 1) return;
int cur = min(sl[i][j], i - lst[j] - 1);
res += G(i - lst[j] - cur, i - lst[j] - 1);
lst[j] += cur;
sl[i][j] -= cur;
}
void solve()
{
FOR(i, 1, n)
{
// Lap day nhung cai truoc do bang nhung cai cung hang
Lap(i, 1);
Lap(i, 2);
if (sl[i][1] > 0)
lst[1] = i;
if (sl[i][2] > 0)
lst[2] = i;
// Lap day nhung cai truoc do bang xu o hang doi dien
{
int n1 = i - lst[1], n2 = i - lst[2];
if (n1 == 0 && n2 > 0)
{
int cur = min(sl[i][1] - 1, n2);
res += cur;
sl[i][1] -= cur;
sl[i][2] += cur;
Lap(i, 2);
}
else if (n1 > 0 && n2 == 0)
{
int cur = min(sl[i][2] - 1, n1);
res += cur;
sl[i][2] -= cur;
sl[i][1] += cur;
Lap(i, 1);
}
}
if (sl[i][1] > 0)
lst[1] = i;
if (sl[i][2] > 0)
lst[2] = i;
// Neu con du thi day len phia truoc
if (sl[i][1])
{
sl[i + 1][1] += sl[i][1] - 1;
res += sl[i][1] - 1;
}
if (sl[i][2])
{
sl[i + 1][2] += sl[i][2] - 1;
res += sl[i][2] - 1;
}
}
cout << res;
}
}
void solve()
{
cin >> n;
FOR(i, 1, n * 2)
{
int x, y; cin >> x >> y;
if (y > 2)
{
res += y - 2;
y = 2;
}
else if (y < 1)
{
res += 1 - y;
y = 1;
}
if (x > n)
{
res += x - n;
x = n;
}
else if (x < 1)
{
res += 1 - x;
x = 1;
}
++sl[x][y];
// dbg(i, x, y, res);
}
AC :: solve();
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
solve();
return 0;
}
