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: Accepted)

#include <stdio.h>
#include <math.h>


  int main()
 {
     long long int N,K,i,j,l,m;

     scanf("%lld %lld",&N, &K);

     if(N<K && K<N/2)
     {
         printf("%lld\n",N);
     }
else if (N<K && K>N/2)
     {
         m=-(N-K);
         if(N>m)
         {
             printf("%lld\n",m);
         }
         else
         {
             printf("%lld\n",N);
         }
     }

    else if(N>=K && ((N%K)==0 || K==1))
     {
         printf("0\n");
     }
     else if(N>K && !(N%K)==0)
     {
        j = N%K;
        l= j-K;
        if(j<l)
         {
             printf("%lld\n",j);
         }
         else
         {
             printf("%lld\n",-l);
         }
     }


     }