#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
int main()
{
  int N;
  cin >> N;
  vector<ll> c(N);
  for (int i = 0; i < N; i++)
  {
    cin >> c[i];
  }
  ll ans = 0;
  if (c[0] < 0)
  {
    ans += abs(c[0]) * 2;
  }
  if (0 < c[N-1])
  {
    ans += abs(c[N-1]) * 2;
  }
  cout << ans << '\n';
  return 0;
}
/*
  File : ~/yukicoder/530/C.cpp
  Date : 2025/03/21
  Time : 21:28:43
*/