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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)



import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.StringTokenizer;


public class Main {
    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
            int n = Integer.parseInt(br.readLine());
            StringTokenizer str = new StringTokenizer(br.readLine(), " ");
            long[] A = new long[n];
            for(int i = 0; i < n ; i++) {
                A[i] = Integer.parseInt(str.nextToken());
            }
            int c1 = func(A,1,n);
            int c2 = func(A,-1,n);
            System.out.println(Math.min(c1,c2));

        } catch (IOException e) {
            System.out.println("error");
        }
    }
    static int func(long[] A,int flg,int n){
        long sum = 0;
        int c = 0;
        for(int i = 0; i < n; i++){
            sum += A[i];
            if(flg == 1){   //次は負
                if(sum >= 0){
                    c += (sum + 1);
                    sum = -1;
                }
                flg = -1;
            }
            else{       //次は正
                if(sum <= 0){
                    c += 1+ (-sum);
                    sum = 1;
                }
                flg = 1;
            }
        }
        return c;
    }
}