import math


def read_file():
    f = open("in.txt")
    nums = ""
    for line in f:
        if line[-1] == "\n":
            line = line[:-1]
        nums += line

    nums = nums.split(" ")
    for i in range(len(nums)):
        nums[i] = int(nums[i])

    nums.sort()

    return nums


def find_n(binominal_coeff):
    n = 3
    while True:
        bc = math.factorial(n)/(math.factorial(2)*math.factorial(n-2))

        if int(bc) == binominal_coeff:
            return n
        else:
            n += 1


def find_smaller_dist(nums, n):
    m = max(nums)


nums = read_file()

n = find_n(len(nums))