#include <bits/stdc++.h>
#define int long long
#define P(x) do {if(debug) cout << x << endl;} while(false)
#define H(x) P(#x << ": " << x)
#define FR(i, a, b) for(int i = (a); i < (b); ++i)
#define F(i, n) FR(i, 0, n)
#define DR(i, a, b) for(int i = (b); i --> (a);)
#define D(i, n) DR(i, 0, n)
#define S(s) (int)(s).size()
#define ALL(x) (x).begin(), (x).end()
#define MI(x, a) (x) = min(x, a)
#define MA(x, a) (x) = max(x, a)
#define V vector
#define pb push_back
#define mp make_pair
#define a coins[0][i]
#define b coins[1][i]
using namespace std;
const bool debug = 1;
const int inf = 1e18;
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int N;
cin>>N;
int res = 0;
vector<vector<int> > coins(2,vector<int> (N+1,-1));
F(i,2*N){
int x,y;
cin>>x>>y;
int X = min(N,max(1ll,x));
int Y = min(2ll,max(1ll,y));
res += abs(X-x) + abs(Y-y);
coins[Y-1][X-1]++;
}
F(i,N){
if(a>b){
swap(coins[0],coins[1]);
}
if(a<0&&b>0){
if(abs(a)>abs(b)){
swap(coins[0],coins[1]);
}
res+=abs(a);
b = a+b;
a = 0;
}
res+=abs(a)+abs(b);
coins[0][i+1] += a;
coins[1][i+1] += b;
}
cout<<res<<endl;
return 0;
}
