#include <bits/stdc++.h>
#define fst first
#define snd second
#define pb push_back
#define forn(i,a,b) for(int i = a; i<b; i++)
#define SZ(x) (int)x.size()
#define ALL(x) x.begin(),x.end()
#define mset(a,v) memset(a,v,sizeof(a))
#define FIN ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
typedef long long ll;
const int rMAXN = 21;
ll dp[rMAXN][1<<rMAXN];
ll n;
pair<ll,ll> p[rMAXN];
ll f(ll x, ll y){
ll &res = dp[x][y];
if(res!=-1) return res;
if(x==2*n) return 0;
res = 10000000000000000;
forn(i,0,2*n) if(!(y&(1<<i))){
ll cost = 0;
cost+=abs(p[i].fst-(1+x/2));
cost+=abs(p[i].snd-(1+(x%2)));
//cout<<x<<" "<<i<<" "<<cost<<'\n';
res=min(res,f(x+1,y|(1<<i))+cost);
}
return res;
}
int main(){ FIN;
cin>>n;
forn(i,0,2*n){
cin>>p[i].fst>>p[i].snd;
}
mset(dp,-1);
ll res = f(0,0);
if(res==10000000000000000){
cout<<-1<<'\n';
}else{
cout<<res<<'\n';
}
return 0;
}
