Recursion-Merge Sort -Problem Statement

Sort an array A using Merge Sort.
Change in the input array itself. So no need to return or print anything.
Input format :
Line 1 : Integer n i.e. Array size
Line 2 : Array elements (separated by space)
Output format :
Array elements in increasing order (separated by space)
Constraints :
1 <= n <= 10^3
Sample Input 1 :
6 
2 6 8 5 4 3
Sample Output 1 :
2 3 4 5 6 8
Sample Input 2 :
5
2 1 5 2 3
Sample Output 2 :
1 2 2 3 5 

****************************Code*******************************

	private static void merge(int[] input, int a[], int b[]) {

		int i = 0, j = 0, k = 0;
		while (i < a.length && j < b.length) {
			if (a[i] < b[j]) {
				input[k] = a[i];
				k++;
				i++;
			} else {
				input[k] = b[j];
				k++;
				j++;
			}
		}
		while (i < a.length) {
			input[k] = a[i];
			k++;
			i++;
		}
		while (j < b.length) {
			input[k] = b[j];
			k++;
			j++;
		}

	}
	public static void mergeSort(int[] input){
	
		if (input.length <= 1)
			return;
		int mid = input.length / 2;
		int[] a = new int[mid];
		int[] b = new int[input.length - mid];
		for (int i = 0; i < mid; i++) {
			a[i] = input[i];
		}
		int k = 0;
		for (int i = mid; i < input.length; i++) {
			b[k] = input[i];
			k++;
		}
		mergeSort(a);
		mergeSort(b);
		merge(input, a, b);
	}