#include <bits/stdc++.h>
#include <bits/extc++.h>
#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define pb(a) push_back(a)
#define eb(a) emplace_back(a)
#define pf(a) push_front(a)
#define ef(a) emplace_front(a)
#define pob pop_back()
#define pof pop_front()
#define mp(a, b) make_pair(a, b)
#define F first
#define S second
#define mt make_tuple
#define gt(t, i) get<i>(t)
#define tomax(a, b) ((a) = max((a), (b)))
#define tomin(a, b) ((a) = min((a), (b)))
#define topos(a) ((a) = (((a) % MOD + MOD) % MOD))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
if(pvaspace) b << " "; pvaspace=true;\
b << pva;\
}\
b << "\n";}
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;
using tiii = tuple<int, int, int>;
const ll MOD = 1000000007;
const ll MAX = 2147483647;
template<typename A, typename B>
ostream& operator<<(ostream& o, pair<A, B> p){
return o << '(' << p.F << ',' << p.S << ')';
}
ll ifloor(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a < 0) return (a - b + 1) / b;
else return a / b;
}
ll iceil(ll a, ll b){
if(b < 0) a *= -1, b *= -1;
if(a > 0) return (a + b - 1) / b;
else return a / b;
}
int main(){
StarBurstStream
int n;
cin >> n;
vector<vector<int>> a(n + 1, vector<int>(3));
ll ans = 0;
for(int i = 1; i <= 2 * n; i++){
ll x, y;
cin >> x >> y;
if(x < 1) ans += 1 - x, x = 1;
else if(x > n) ans += x - n, x = n;
if(y < 1) ans += 1 - y, y = 1;
else if(y > 2) ans += y - 2, y = 2;
a[x][y]++;
}
for(int i = 1; i <= n; i++)
for(int j = 1; j <= 2; j++) a[i][j]--;
for(int x = 1; x <= n; x++){
if(a[x][1] < 0 && a[x][2] > 0){
int tmp = min(-a[x][1], a[x][2]);
ans += tmp;
a[x][1] += tmp; a[x][2] -= tmp;
}
if(a[x][1] > 0 && a[x][2] < 0){
int tmp = min(a[x][1], -a[x][2]);
ans += tmp;
a[x][1] -= tmp; a[x][2] += tmp;
}
if(x == n){
assert(a[x][1] == 0 && a[x][2] == 0);
break;
}
ans += abs(a[x][1]) + abs(a[x][2]);
a[x + 1][1] += a[x][1]; a[x][1] = 0;
a[x + 1][2] += a[x][2]; a[x][2] = 0;
//cerr << "test " << x << "\n";
//for(int i = 1; i <= 2; i++){
//for(int j = 1; j <= n; j++) cerr << a[j][i] << " ";
//cerr << "\n";
//}
}
cout << ans << "\n";
return 0;
}
