static int binarySearch(int[] arr, int target) {
        int low = 0 ;
        int high = arr.length - 1 ;

        while(low <= high) {
            int mid =(low + high) / 2;

            if(arr[mid] == target) {
                return mid;
            }
            else if(arr[mid] > target) {
                high = mid - 1;
            }
            else {
                low = mid + 1;
            }

        }
        return -1;
    }