import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
ulong bignum = 1_000_000_007;
alias Pair = Tuple!(long, "begin", long, "end");

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void main()
{
    auto n = lread();
    auto a = aryread();
    long cost_odd, cost_even; // head one grater than 0
    long c_sum_odd, c_sum_even;
    foreach (i, e; a)
    {
        if (!(i % 2))
        {
            if (c_sum_odd + e > 0)
                c_sum_odd += e;
            else
            {
                cost_odd += 1 - (c_sum_odd + e);
                c_sum_odd = 1;
                // writefln("cost_odd = %s, i = %s", cost_odd, i);
            }
        }
        else
        {
            if(c_sum_odd + e < 0)
                c_sum_odd += e;
            else
            {
                cost_odd += 1 + c_sum_odd + e;
                c_sum_odd = -1;
                // writefln("cost_odd = %s, i = %s", cost_odd, i);
            }
        }
    }
    foreach (i, e; a)
    {
        if (!(i % 2))
        {
            if (c_sum_even + e < 0)
                c_sum_even += e;
            else
            {
                cost_even += 1 + c_sum_even + e;
                c_sum_even = -1;
                // writefln("cost_even = %s, i = %s", cost_even, i);
            }
        }
        else
        {
            if(c_sum_even + e > 0)
                c_sum_even += e;
            else
            {
                cost_even += 1 - (c_sum_even + e);
                c_sum_even = 1;
                // writefln("cost_even = %s, i = %s", cost_even, i);
            }
        }
    }
    min(cost_even, cost_odd).writeln();
}