#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
#define range(i, n) for (int i = 0; i < (n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define ar array
using namespace std;
// using namespace __gnu_pbds;
/*
typedef tree<
int,
null_type,
less<int>,
rb_tree_tag,
tree_order_statistics_node_update>
ordered_set;
*/
typedef long long ll;
typedef double ld;
typedef unsigned long long ull;
const int INFi = 1e9 + 5;
const int maxN = 2e5 + 5;
const int md = 998244353;
const ll INF = 2e18;
double getTime() { return clock() / (double) CLOCKS_PER_SEC; }
void solve() {
int n;
cin >> n;
vector<vector<int>> cnt(2, vector<int> (n + 1));
ll ans = 0;
range(_, 2 * n) {
int x, y;
cin >> x >> y;
if (y < 1) {
ans += 1 - y;
y = 1;
} else if (y > 2) {
ans += y - 2;
y = 2;
}
if (x < 1) {
ans += 1 - x;
x = 1;
} else if (x > n) {
ans += x - n;
x = n;
}
cnt[y - 1][x]++;
}
n++;
int i = 0, j = 0;
cnt[0][0] = cnt[1][0] = 1;
for(int e = 1; e < n; ++e) {
if (i == e - 1 && j == e - 1) {
ans += cnt[0][i] - 1;
cnt[0][e] += cnt[0][i] - 1;
cnt[0][i] = 1;
ans += cnt[1][j] - 1;
cnt[1][e] += cnt[1][j] - 1;
cnt[1][j] = 1;
} else {
while(cnt[0][e] && i != e - 1) {
i++;
cnt[0][i] = 1;
cnt[0][e]--;
ans += e - i;
}
while(cnt[1][e] && j != e - 1) {
j++;
cnt[1][j] = 1;
cnt[1][e]--;
ans += e - j;
}
}
if (j == e - 1 && cnt[1][e]) j++;
if (i == e - 1 && cnt[0][e]) i++;
while(cnt[0][e] > 1 && j != e) {
j++;
cnt[0][e]--;
cnt[1][j] = 1;
ans += e - j + 1;
}
while(cnt[1][e] > 1 && i != e) {
i++;
cnt[1][e]--;
cnt[0][i] = 1;
ans += e - i + 1;
}
}
cout << ans << '\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
// cout << setprecision(15) << fixed;
int tests = 1;
// cin >> tests;
range(_, tests) {
solve();
}
return 0;
}
