#include <bits/stdc++.h>
using namespace std;
long long memo[100001][2];
int inp[100001], n;
bool sudah[100001][2];
long long depe(int ix, int positip) {
  if (ix == 0) {
    if (positip == 0)
      return abs(inp[0] + 1);
    else
      return abs(inp[0] - 1);
  } else {
    if (sudah[ix][positip]) return memo[ix][positip];
    sudah[ix][positip] = true;
    if (positip == 0)
      return memo[ix][positip] = min(depe(ix - 1, 0) + abs(inp[ix] - 1),
                                     depe(ix - 1, 1) + abs(inp[ix] + 1));
    else
      return memo[ix][positip] = min(depe(ix - 1, 0) + abs(inp[ix] + 1),
                                     depe(ix - 1, 1) + abs(inp[ix] - 1));
  }
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> inp[i];
  }
  cout << depe(n - 1, 1) << endl;
}
