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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
int *vec;
int sinal(int a){
	if(a < 0) return -1;
	return 1;
}
int a = 0xEDU;
long long int min(long long a, long long b){return a > b ? b: a;}
int main(){
	int n, sumpos = 0, sumneg = 0;//, read;
	long long int altops = 0, altneg = 0;
	scanf("%d", &n);
	vec = malloc(sizeof(int) * n*2);
	for(int i = 0; i < n; ++i){
		scanf("%d", &vec[i]);
	}
	for(int i = 0; i < n; ++i){
		int sinalobjetivo = sinal(-(i%2));
		int toalt = -sumpos  -vec[i] +sinalobjetivo;
		if(sumpos + vec[i] != 0){
			if(sinal(sumpos + vec[i]) == sinalobjetivo){
				sumpos += vec[i];
				continue;
			}
		}else{
			toalt = sinalobjetivo;
		}
		sumpos += toalt + vec[i];
		altops += abs(toalt);
		//printf("p %d, %d\n", i, toalt);
	}
	for(int i = 0; i < n; ++i){
		int sinalobjetivo = sinal(-((i+1)%2));
		int toalt = -sumneg  -vec[i] +sinalobjetivo;
		if(sumneg + vec[i] != 0){
			if(sinal(sumneg +vec[i]) == sinalobjetivo){
				sumneg += vec[i];
				continue;
			}
		}else{
			toalt = sinalobjetivo;
		}
		sumneg += toalt + vec[i];
		altneg += abs(toalt);
		//printf("i %d, %d\n", i, toalt);

	}
		//printf("p %d %d n %d %d");
	printf("%lld %lld\n", /*min(*/altops, altneg)/*)*/;
}