Problem:
Score : 100 points

Problem Statement

You are given a 4-character string S consisting of uppercase English letters.
Determine if S consists of exactly two kinds of characters which both appear twice in S.

Constraints

The length of S is 4.

S consists of uppercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If S consists of exactly two kinds of characters which both appear twice in S, print Yes; otherwise, print No.

Sample Input 1

ASSA

Sample Output 1

Yes

S consists of A and S which both appear twice in S.

Sample Input 2

STOP

Sample Output 2

No

Sample Input 3

FFEE

Sample Output 3

Yes

Sample Input 4

FREE

Sample Output 4

No

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)



def solve()
  input = readline()
  array = []
  cnt = 0
  s1 = input[0]
  s2 = input[1]
  
  i1 = input.count(s1)
  i2 = input.count(s2)
  if i1 == 2 && i2 == 2 then
    puts "Yes"
  else
    puts "No"
  end
end

solve()