public static int longestFlat(int[] arr)
    {
        return longestFlat(arr,0,0,arr[0],arr[1],0,0);
    }

    private static int longestFlat(int [] arr, int i,int j, int first, int second,int count,int max)
    {
        if(count > max)
            max = count;

        if(i==arr.length)
            return max;

        if((second == first || second == first + 1 || first==second-1) &&
        (arr[i] == first || arr[i] == second || arr[i] == first+1 || arr[i] == first-1 )){
            return longestFlat(arr, i+1,j, first, second, count+1, max);
        }
        else{
            if(i>arr.length-1)
            {
                j++;
                i=j;
                first = arr[i];
                second = arr[i+1];
                count=0;
                return longestFlat(arr, i, j, first,second, count,max);
            }
            return max;

        }

    }