#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <set>
#include <utility>
#include <string>
#include <cstring>
#include <queue>
#include <cmath>
#include <iomanip>
#include <cassert>
#include <numeric>
#define EPS 1e-9
#define INF 1070000000LL
#define MOD 1000000007LL
#define fir first
#define foreach(it,X) for(auto it=(X).begin();it!=(X).end();it++)
#define numa(x,a) for(auto x: a)
#define ite iterator
#define mp make_pair
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define pb push_back
#define pf push_front
#define sec second
#define sz(x) ((int)(x).size())
#define ALL( c ) (c).begin(), (c).end()
#define gcd(a,b) __gcd(a,b)
#define mem(x,n) memset(x,n,sizeof(x))
#define endl "\n"
using namespace std;
template <int POS, class TUPLE> void deploy(std::ostream &os, const TUPLE &tuple){}
template <int POS, class TUPLE, class H, class ...Ts> void deploy(std::ostream &os, const TUPLE &t){ os << (POS == 0 ? "" : ", ") << get<POS>(t); deploy<POS + 1, TUPLE, Ts...>(os, t); }
template <class T,class U> std::ostream& operator<<(std::ostream &os, std::pair<T,U> &p){ os << "(" << p.first <<", " << p.second <<")";return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::vector<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T> std::ostream& operator<<(std::ostream &os, std::set<T> &v){ int remain = v.size(); os << "{"; for(auto e: v) os << e << (--remain == 0 ? "}" : ", "); return os; }
template <class T, class K> std::ostream& operator<<(std::ostream &os, std::map<T, K> &mp){ int remain = mp.size(); os << "{"; for(auto e: mp) os << "(" << e.first << " -> " << e.second << ")" << (--remain == 0 ? "}" : ", "); return os; }
#define DEBUG1(var0) { std::cerr << (#var0) << "=" << (var0) << endl; }
#define DEBUG2(var0, var1) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG1(var1); }
#define DEBUG3(var0, var1, var2) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG2(var1,var2); }
#define DEBUG4(var0, var1, var2, var3) { std::cerr << (#var0) << "=" << (var0) << ", ";DEBUG3(var1,var2,var3); }
using ll = long long;

ll calc(const vector<int> &nums, ll x) {
  ll ret = abs
    (x - nums.front());
  ll cur = x;
  bool plus = x < 0;
  rep2(i,1,sz(nums)) {
    cur += nums[i];
    if (plus) {
      if (cur <= 0) {
        ret += 1 - cur;
        cur = 1;
      }
    } else {
      if (cur >= 0) {
        ret += cur + 1;
        cur = -1;
      }
    }
    plus = !plus;
  }
  return ret;
}

ll calc2(ll lp, ll up, const vector<int> &nums) {
  while (up - lp >= 3) {
    ll p1 = lp + (up - lp) / 3;
    ll p2 = lp + (up - lp) / 3 * 2;
    ll p1v = calc(nums, p1);
    ll p2v = calc(nums, p2);
    if (p1v < p2v) {
      up = p2;
    } else {
      lp = p1;
    }
  }
  vector<ll> vs;
  for (ll i = lp; i <= up; i++) {
    vs.pb(calc(nums,i));
  }
  return *min_element(ALL(vs));
}

int main()
{
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  int N;
  cin >> N;
  vector <int> nums(N);
  rep(i, N) {
    cin >> nums[i];
  }
  auto x = calc2(-1e14-30,-1,nums);
  auto y = calc2(1,1e14+30,nums);
  cout << min(x,y) << endl;
  return 0;
}



Measured memory_bytes: 640