#include <bits/stdc++.h> #define fst first #define snd second #define pb push_back #define SZ(x) (int)x.size() #define ALL(x) x.begin(),x.end() #define forn(i,a,b) for(int i = a; i<b; i++) #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 MAXN = 3000+5; ll n; ll dp[MAXN][MAXN]; vector<pair<ll,ll>> p; ll f(ll x, ll y){ ll &res=dp[x][y]; if(res!=-1) return res; if(x==2*n && y==n) return 0; if(x==2*n) return 100000000000000000; res=100000000000000000; pair<ll,ll> p1 = {1+x-y,1}; pair<ll,ll> p2 = {1+y,2}; res=min(res,f(x+1,y+1)+abs(p[x].fst-p2.fst)+abs(p[x].snd-p2.snd)); res=min(res,f(x+1,y)+abs(p[x].fst-p1.fst)+abs(p[x].snd-p1.snd)); return res; } bool comp(const pair<ll,ll> &a, const pair<ll,ll> &b){ if(a.fst<b.fst) return true; if(a.fst>b.fst) return false; if(abs(a.snd-1)<abs(b.snd-1)) return true; return false; } int main(){ cin>>n; p.clear(); p.resize(2*n); forn(i,0,2*n) cin>>p[i].fst>>p[i].snd; sort(ALL(p),comp); mset(dp,-1); ll res = f(0,0); if(res>=100000000000000000){ cout<<-1<<'\n'; }else cout<<res<<'\n'; return 0; }