Problem:
Score : 300 points

Problem Statement

You are given an integer sequence of length N. The i-th term in the sequence is a_i.
In one operation, you can select a term and either increment or decrement it by one.

At least how many operations are necessary to satisfy the following conditions?

For every i (1≤i≤n), the sum of the terms from the 1-st through i-th term is not zero.

For every i (1≤i≤n-1), the sign of the sum of the terms from the 1-st through i-th term, is different from the sign of the sum of the terms from the 1-st through (i+1)-th term.

Constraints

2 ≤ n ≤ 10^5

|a_i| ≤ 10^9

Each a_i is an integer.

Input

Input is given from Standard Input in the following format:

n
a_1 a_2 ... a_n

Output

Print the minimum necessary count of operations.

Sample Input 1

4
1 -3 1 0

Sample Output 1

4

For example, the given sequence can be transformed into 1, -2, 2, -2 by four operations. The sums of the first one, two, three and four terms are 1, -1, 1 and -1, respectively, which satisfy the conditions.

Sample Input 2

5
3 -6 4 -5 7

Sample Output 2

0

The given sequence already satisfies the conditions.

Sample Input 3

6
-1 4 3 2 -5 4

Sample Output 3

8

Solution in JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

'use strict'
let input = require("fs").readFileSync("/dev/stdin", "utf8");
let Nums = input.split('\n');
let amount = Nums[0]*1;
let arr = Nums[1].split(" ").map(x => x*1);
let isPrus = arr[0] > 0? true: false;
let sum = 0;
let ans = 0;
for(let i = 0; i < amount; i++){
	//console.log(arr[i])
  	//console.log(isPrus)
  	sum += arr[i];
  	if(sum > 0 != isPrus){
      	ans += Math.abs(sum);
      	sum = 0;
    }
  	// 足し合わせが0になった時も合わせて処理
  	if(sum == 0){
    	if(isPrus){
        	sum = 1;
          	ans += 1;
        } else {
            sum = -1;
          	ans += 1;
        }
    }  
  	isPrus = !isPrus;
}

console.log(ans);