#include <bits/stdc++.h> #define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x) #define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x) typedef long long ll; typedef std::pair<int, int> pii; typedef std::pair<ll , ll > pll; using namespace std; const int N = 100'010; int a[2][N]; int n; int main() { cin.tie(0) -> sync_with_stdio(false); memset(a, -1, sizeof(a)); ll ans = 0; cin >> n; Loop (i,0,2*n) { int x, y; cin >> x >> y; if (x < 1) { ans += 1-x; x = 1; } if (x > n) { ans += x-n; x = n; } if (y < 1) { ans += 1-y; y = 1; } if (y > 2) { ans += y-2; y = 2; } a[y-1][x-1]++; } Loop (i,0,n) { if ((a[0][i] < 0) != (a[1][i] < 0)) { int mv = min(abs(a[0][i]), abs(a[1][i])); ans += mv; a[0][i] += a[0][i] < 0? mv: -mv; a[1][i] += a[1][i] < 0? mv: -mv; } ans += abs(a[0][i]) + abs(a[1][i]); a[0][i+1] += a[0][i]; a[1][i+1] += a[1][i]; } cout << ans << '\n'; }