Problem:
Score : 100 points

Problem Statement

You are given three integers, A, B and C.

Among them, two are the same, but the remaining one is different from the rest.

For example, when A=5,B=7,C=5, A and C are the same, but B is different.

Find the one that is different from the rest among the given three integers.

Constraints

-100 \leq A,B,C \leq 100

A, B and C are integers.

The input satisfies the condition in the statement.

Input

Input is given from Standard Input in the following format:

A B C

Output

Among A, B and C, print the integer that is different from the rest.

Sample Input 1

5 7 5

Sample Output 1

7

This is the same case as the one in the statement.

Sample Input 2

1 1 7

Sample Output 2

7

In this case, C is the one we seek.

Sample Input 3

-100 100 100

Sample Output 3

-100

Solution in Ruby (2.3.3) (judge verdict: Runtime Error)

(N, K), *XYs = readlines.map{|l| l.split.map(&:to_i)}

xs, ys = XYs.transpose.map(&:sort)
cnt, c = 0, Array.new(N + 1){Array.new(N + 1, 0)}
xs.each_with_index do |x, i|
  ys.each_with_index do |y, j|
    cnt += 1 if XYs.member?([x, y])
    c[i + 1][j + 1] = cnt
  end
end
ans = 1e20.to_i
[*0 ... N].repeated_combination(2) do |i, j|
  next unless c[j + 1][j + 1] - c[i][j] - c[j][i] + c[i][i] >= K
  s = (xs[j] - xs[i]) * (ys[j] - ys[i])
  ans = s if s < ans
end
puts ans