Title:
   

Description
Consider the natural numbers from 1 to N. By associating to each number a sign (+ or -) and calculating the value of this expression we obtain a sum S. The problem is to determine for a given sum S the minimum number N for which we can obtain S by associating signs for all numbers between 1 to N.

For a given S, find out the minimum value N in order to obtain S according to the conditions of the problem.

Input
The only line contains in the first line a positive integer S (0< S <= 100000) which represents the sum to be obtained.

Output
The output will contain the minimum number N for which the sum S can be obtained.

Sample Input

12

Sample Output

7

Hint
The sum 12 can be obtained from at least 7 terms in the following way: 12 = -1+2+3+4+5+6-7.

Realization:

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    int sum, input, output;
   
    sum = 0;
    output = 1;
   
    scanf("%d", &input);
   
    while(sum < input || ((sum - input)%2 == 1))
    {
          sum += output;
          output ++;
    }
   
    printf("%d\n", output - 1);
    getch();
    return 0;
}

comment:

如果输入的整数为S, sum = 1 + 2 + 3 + ... + N , 当sum > S 时,令sum - S = 2p ,p属于1-----N中的某一个,令p为-p

则sum1 = 1 + 2 + ... -p +... + N = sum - 2*p = S,因此我们只要满足这些条件就可以求得我们要求得解.