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

alias sread = () => readln.chomp();
alias Point2 = Tuple!(long, "y", long, "x");

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;
    }
}

enum MOD = (10 ^^ 9) + 7;

void main()
{
    long N = lread();
    auto A = aryread();
    foreach (i; 1 .. N)
    {
        A[i] += A[i - 1];
    }
    long ans = long.max;
    foreach (B; [true, false])
    {
        long cnt;
        long x;
        foreach (i; 0 .. N)
        {
            if (B == (i & 1))
            {
                long tmp = (A[i] + x <= 0) ? abs(A[i] + x) + 1 : 0;
                x += tmp;
                cnt += tmp;
            }
            else
            {
                long tmp = (0 <= A[i] + x) ? abs(A[i] + x) + 1 : 0;
                x -= tmp;
                cnt += tmp;
            }
        }
        ans = ans.min(cnt);
    }
    writeln(ans);
}
