Thought to share my code in java :

public static void main(String[] args) {
     Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k=in.nextInt();
        int count=0;
        int a[]=new int[n];
        for(int i=0; i < n; i++){
             a[i] = in.nextInt();
         }
        int b[]=new int[k+1];

        for(int i=0;i<n;i++)
        {
            b[a[i]%k]=b[a[i]%k]+1;
        }
        int cond=(k%2==0)?k/2:(k/2)+1;
       for(int j=0;j<cond;j++)
       {
           if(b[0]!=0&&j==0)
               count++;
           else
           count+=(b[j]>b[k-j])?b[j]:b[k-j];
       }
       if(k%2==0)
           count+=1;
        System.out.println(count);

in.close(); }