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>

long long int n;

long long int count(long long int a0){
    long long int a,i,S[2],C[2]={};
    S[0]=a0;
    S[1]=a0;
    for(i=1;i<n;i++){
        scanf("%lld",&a);
        S[0]+=a;
        S[1]+=a;
        if(i%2==1){
            if(S[0]<=0){
                C[0] += -1*S[0] + 1;
                S[0] = 1;
            }
            if(S[1]>=0){
                C[1] += S[1] + 1;
                S[1] = -1;
            }
        }
        else{
            if(S[0]>=0){
                C[0] += S[0] + 1;
                S[0] = -1;
            }
            if(S[1]<=0){
                C[1] += -1*S[1] + 1;
                S[1] = 1;
            }
        }
    }
    return C[0]<C[1]?C[0]:C[1];
}

int main()
{
    long long int a,ans;
    scanf("%lld %lld",&n,&a);
    if(a==0){
        ans = count(1)<count(-1) ? count(1)+1 : count(-1)+1;
    }
    else{
        ans = count(a);
    }
    printf("%lld\n",ans);
    return 0;
}