Problem:
Score : 300 points

Problem Statement

Given any integer x, Aoki can do the operation below.

Operation: Replace x with the absolute difference of x and K.

You are given the initial value of an integer N. Find the minimum possible value taken by N after Aoki does the operation zero or more times.

Constraints

0 ≤ N ≤ 10^{18}

1 ≤ K ≤ 10^{18}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the minimum possible value taken by N after Aoki does the operation zero or more times.

Sample Input 1

7 4

Sample Output 1

1

Initially, N=7.

After one operation, N becomes |7-4| = 3.

After two operations, N becomes |3-4| = 1, which is the minimum value taken by N.

Sample Input 2

2 6

Sample Output 2

2

N=2 after zero operations is the minimum.

Sample Input 3

1000000000000000000 1

Sample Output 3

0

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

#include<stdio.h>
long long abc(long long a,long long b)
{   long long c;
    c=a-b;
    if(c<0) c=-c;
    return c;
}
int main()
{  long long n,k,n1;
   int f=1;
   scanf("%lld%lld",&n,&k);
   n1=n;
   if(n==0) printf("%lld",k);
   else if(k==1||k==n) printf("0");
   else
   {  if(n>k) n=n%k;
         else n=k%n;
	  while(f)
      {  
        n=abc(n,k);
        if(n1>n) n1=n;
        else 
	    {  printf("%lld",n1);
	       f=0;
	    }
      }
   }
}