def pickingNumbers(a):
    # Write your code here
    a.sort()
    result = [[a[0]]]
    last_index = 1
    for item in result:
        for index in range(last_index, len(a)):
            last_index += 1
            if (abs(min(item) - a[index]) <= 1):
                item.append(a[index])
            else:
                result.append([a[index]])
                break
    return len(sorted(result, key=lambda x: len(x))[-1])