/***Farhan132***/
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
//#pragma GCC optimization ("unroll-loops")
//#pragma GCC optimize("fast-math")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double dd;
typedef vector<ll> vll;
typedef pair<ll , ll> ii;
typedef vector< ii > vii;
typedef pair < pair < ll , ll > , pair < ll , ll > > cm;
typedef tuple < ll, ll, ll > tp;
#define ff first
#define ss second
#define pb push_back
#define in insert
#define f0(b) for(int i=0;i<(b);i++)
#define f00(b) for(int j=0;j<(b);j++)
#define f1(b) for(int i=1;i<=(b);i++)
#define f11(b) for(int j=1;j<=(b);j++)
#define f2(a,b) for(int i=(a);i<=(b);i++)
#define f22(a,b) for(int j=(a);j<=(b);j++)
#define sf(a) scanf("%lld",&a)
#define sff(a,b) scanf("%lld %lld", &a , &b)
#define pf(a) printf("%lld\n",a)
#define pff(a,b) printf("%lld %lld\n", a , b)
#define bug printf("**!\n")
#define mem(a , b) memset(a, b ,sizeof(a))
#define front_zero(n) __builtin_clzll(n)
#define back_zero(n) __builtin_ctzll(n)
#define total_one(n) __builtin_popcount(n)
#define clean fflush(stdout)
//const ll mod = (ll) 998244353;
const ll mod = (ll) 1e9 + 7;
const ll maxn = (ll)1e8 + 5;
const int nnn = 1048590;
//const int inf = numeric_limits<int>::max()-1;
const int inf = 1e9;
//const ll INF = numeric_limits<ll>::max()-1;
const ll INF = (ll)1e18;
ll dx[]={0,1,0,-1};
ll dy[]={1,0,-1,0};
ll dxx[]={0,1,0,-1,1,1,-1,-1};
ll dyy[]={1,0,-1,0,1,-1,1,-1};
bool USACO = 0;
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const ll N = 1e5 + 5;
ll cnt[N][4];
void solve(){
ll n; cin >> n;
mem(cnt, -1); ll ans = 0;
for(ll i = 1; i <= 2*n; i++){
ll x, y;
cin >> x >> y;
if(x < 1) ans += abs(x - 1) , x = 1;
if(x > n) ans += abs(n - x) , x = n;
if(y < 1) ans += abs(y - 1) , y = 1;
if(y > 2) ans += abs(y - 2) , y = 2;
cnt[x][y]++;
}
for(ll i = 1; i <= n; i++){
vector < ll > c(3, 1);
if(cnt[i][1] < 0) c[1] = -1;
if(cnt[i][2] < 0) c[2] = -1;
if(c[1] != c[2]){
ll donate = min(c[1] * cnt[i][1] , c[2] * cnt[i][2]);
cnt[i][1] += c[2] * donate;
cnt[i][2] += c[1] * donate;
ans += donate;
}
ans += abs(cnt[i][1]) + abs(cnt[i][2]);
cnt[i + 1][1] += cnt[i][1];
cnt[i + 1][2] += cnt[i][2];
}
cout << ans << '\n';
return;
}
int main() {
#ifdef LOCAL
freopen("in", "r", stdin);
freopen("out", "w", stdout);
auto start_time = clock();
#else
ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#endif
ll T = 1, CT = 0; //cin >> T;
while(T--){
solve();
}
#ifdef LOCAL
auto end_time = clock();
cerr<< "Execution time: "<<(end_time - start_time)*(int)1e3/CLOCKS_PER_SEC<<" ms\n";
#endif
return 0;
}
