#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; }