Problem:
Score : 100 points

Problem Statement

You are given two integers a and b.
Determine if a+b=15 or a\times b=15 or neither holds.

Note that a+b=15 and a\times b=15 do not hold at the same time.

Constraints

1 \leq a,b \leq 15

All values in input are integers.

Input

Input is given from Standard Input in the following format:

a b

Output

If a+b=15, print +;
if a\times b=15, print *;
if neither holds, print x.

Sample Input 1

4 11

Sample Output 1

+

4+11=15.

Sample Input 2

3 5

Sample Output 2

*

3\times 5=15.

Sample Input 3

1 1

Sample Output 3

x

1+1=2 and 1\times 1=1, neither of which is 15.

Solution in Ruby (2.3.3) (judge verdict: Accepted)

def main(argv)
  a, b = gets.split(' ').map(&:to_i)
  if a + b == 15 then
    puts '+'
  elsif a * b == 15 then
    puts '*'
  else
    puts 'x'
  end
end

if self.to_s == 'main' then
  main(ARGV)
end