#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MXN = 1e5+5;
int n, a[MXN][2];
ll ans;
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n;
for(int i=1,x,y; i<=2*n; i++) {
cin >> x >> y;
if(y>=2) {
ans += y-2;
y = 2;
}
else {
ans += 1-y;
y = 1;
}
if(x<1) {
ans += 1-x;
x = 1;
}
if(x>n) {
ans += x-n;
x = n;
}
a[x][y-1]++;
}
for(int i=1; i<=n; i++) {
a[i][0] += a[i-1][0] - 1;
a[i][1] += a[i-1][1] - 1;
for(int t : {0, 1})
if(a[i][t]>0 && 0>a[i][t^1]) {
int x = min(a[i][t], -a[i][t^1]);
a[i][t] -= x;
a[i][t^1] += x;
ans += x;
}
ans += abs(a[i][0]);
ans += abs(a[i][1]);
}
cout << ans << '\n';
return 0;
}
