Problem:
Score : 500 points

Problem Statement

Snuke, who loves animals, built a zoo.

There are N animals in this zoo. They are conveniently numbered 1 through N, and arranged in a circle.
The animal numbered i (2≤i≤N-1) is adjacent to the animals numbered i-1 and i+1. Also, the animal numbered 1 is adjacent to the animals numbered 2 and N, and the animal numbered N is adjacent to the animals numbered N-1 and 1.

There are two kinds of animals in this zoo: honest sheep that only speak the truth, and lying wolves that only tell lies.

Snuke cannot tell the difference between these two species, and asked each animal the following question: "Are your neighbors of the same species?" The animal numbered i answered s_i. Here, if s_i is o, the animal said that the two neighboring animals are of the same species, and if s_i is x, the animal said that the two neighboring animals are of different species.

More formally, a sheep answered o if the two neighboring animals are both sheep or both wolves, and answered x otherwise.
Similarly, a wolf answered x if the two neighboring animals are both sheep or both wolves, and answered o otherwise.

Snuke is wondering whether there is a valid assignment of species to the animals that is consistent with these responses. If there is such an assignment, show one such assignment. Otherwise, print -1.

Constraints

3 ≤ N ≤ 10^{5}

s is a string of length N consisting of o and x.

Input

The input is given from Standard Input in the following format:

N
s

Output

If there does not exist an valid assignment that is consistent with s, print -1.
Otherwise, print an string t in the following format. The output is considered correct if the assignment described by t is consistent with s.

t is a string of length N consisting of S and W.

If t_i is S, it indicates that the animal numbered i is a sheep. If t_i is W, it indicates that the animal numbered i is a wolf.

Sample Input 1

6
ooxoox

Sample Output 1

SSSWWS

For example, if the animals numbered 1, 2, 3, 4, 5 and 6 are respectively a sheep, sheep, sheep, wolf, wolf, and sheep, it is consistent with their responses. Besides, there is another valid assignment of species: a wolf, sheep, wolf, sheep, wolf and wolf.

Let us remind you: if the neiboring animals are of the same species, a sheep answers o and a wolf answers x. If the neiboring animals are of different species, a sheep answers x and a wolf answers o.

Sample Input 2

3
oox

Sample Output 2

-1

Print -1 if there is no valid assignment of species.

Sample Input 3

10
oxooxoxoox

Sample Output 3

SSWWSSSWWS

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

# 解説を参照済
def candidates(n, answers)
  _candidates = [ %w(S S), %w(S W), %w(W W), %w(W S) ]
  _candidates.each do |animals|
    (1..(n - 2)).each do |i|
      if animals[i - 1] == 'S' && animals[i] == 'S'
        if answers[i] == 'o'
          animals.push 'S'
        else
          animals.push 'W'
        end
      end
      if animals[i - 1] == 'W' && animals[i] == 'S'
        if answers[i] == 'o'
          animals.push 'W'
        else
          animals.push 'S'
        end
      end
      if animals[i - 1] == 'S' && animals[i] == 'W'
        if answers[i] == 'o'
          animals.push 'W'
        else
          animals.push 'S'
        end
      end
      if animals[i - 1] == 'W' && animals[i] == 'W'
        if answers[i] == 'o'
          animals.push 'S'
        else
          animals.push 'W'
        end
      end
    end
  end
end

def f(n, s)
  answers = s.split('')
  _candidates = candidates(n, answers)
  a_n = answers[n - 1]

  ans = _candidates
  list = answers

  ans.each do |ans_seq|
    if (ans_seq[0] == "S" && list[0] == "o") ||
       (ans_seq[0] == "W" && list[0] == "x")
      next unless (ans_seq[1] == ans_seq[n-1])
    else
      next unless (ans_seq[1] != ans_seq[n-1])
    end
 
    if (ans_seq[n-1] == "S" && list[n-1] == "o") ||
       (ans_seq[n-1] == "W" && list[n-1] == "x")
      next unless (ans_seq[0] == ans_seq[n-2])
    else
      next unless (ans_seq[0] != ans_seq[n-2])
    end
    # solve
    return ans_seq.join
  end
  -1

##  require 'pp'
##  pp _candidates.map(&:join)
#  valid_candidate = nil
#  _candidates.each do |candidate|
#    c = candidate[n - 1]
#    c_prev = candidate[n - 2]
#    c_next = candidate[0]
##    puts c
##    puts c_prev
##    puts c_next
#    valid =
#      if c == 'S'
#        if a_n == 'o'
#          c_prev == 'S' && c_next == 'S' || c_prev == 'W' && c_next == 'W'
#        else
#          c_prev == 'S' && c_next == 'W' || c_prev == 'W' && c_next == 'S'
#        end
#      else
#        if a_n == 'o'
#          c_prev == 'S' && c_next == 'W' || c_prev == 'W' && c_next == 'S'
#        else
#          c_prev == 'S' && c_next == 'S' || c_prev == 'W' && c_next == 'W'
#        end
#      end
#    if valid
#      valid_candidate = candidate.join
#      break
#    end
#  end
#  valid_candidate || -1
end

n = STDIN.gets.to_i
s = STDIN.gets
puts f(n, s)