#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cmath>
#include <map>
#include <queue>
#include <iomanip>
#include <set>
#include <tuple>
#define mkp make_pair
#define mkt make_tuple
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
const ll MOD=1e9+7;
template<class T> void chmin(T &a,const T &b){if(a>b) a=b;}
template<class T> void chmax(T &a,const T &b){if(a<b) a=b;}

const ll INF=1e15;

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);

  int N;
  cin>>N;
  vector<ll> A(N);
  rep(i,N) cin>>A[i];

  ll ans=INF;
  {
    vector<ll> val(N,0);
    set<ll> se;
    rep(i,N){
      auto itr=se.upper_bound(A[i]);
      if(itr==se.end()) val[i]=INF;
      else val[i]+=abs(*(itr));
      se.insert(A[i]);
    }
    se.clear();
    for(int i=N-1;i>=0;i--){
      auto itr=se.upper_bound(A[i]);
      if(itr==se.end()) val[i]=INF;
      else val[i]+=abs(*(itr));
      se.insert(A[i]);
    }

    for(int i=0;i<N;i++){
      if(val[i]>=INF) continue;
      chmin(ans,val[i]+abs(A[i]));
    }
  }

  {
    vector<ll> val(N,0);
    ll mi=INF;
    rep(i,N){
      if(mi<A[i]) val[i]+=mi;
      else val[i]+=INF;
      chmin(mi,A[i]);
    }
    mi=INF;
    for(int i=N-1;i>=0;i--){
      if(mi<A[i]) val[i]+=mi;
      else val[i]+=INF;
      chmin(mi,A[i]);
    }

    rep(i,N){
      if(val[i]>=INF) continue;
      chmin(ans,val[i]+A[i]);
    }
  }

  if(ans==INF) cout<<-1<<endl;
  else cout<<ans<<endl;


  return 0;
}