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 PHP (5.6.30) (judge verdict: Accepted)

<?php
class main {
    var $word = array();
    var $ans = array();
    function run () {
        fscanf(STDIN, "%d", $n);
        $line = trim(fgets(STDIN));
        $this->word = str_split($line);
        for ($a = 0; $a < 2; $a++) {
            for ($b = 0; $b < 2; $b++) {
                $this->ans[0] = $a;
                $this->ans[1] = $b;
                for ($i = 1; $i <= $n; $i++) {
                    if ($this->word[$i%$n] == "o") {
                        if ($this->ans[$i%$n]) {
                            $this->ans[($i + 1)%$n] = $this->ans[$i - 1];
                        } else {
                            $this->ans[($i + 1)%$n] = !$this->ans[$i - 1];
                        }
                    } else {
                        if ($this->ans[$i%$n]) {
                            $this->ans[($i + 1)%$n] = !$this->ans[$i - 1];
                        } else {
                            $this->ans[($i + 1)%$n] = $this->ans[$i - 1];
                        }
                    }
                }
                if ($this->ans[0] == $a && $this->ans[1] == $b) {
                    foreach ($this->ans as $k => $v) {
                        echo $v?"S":"W";
                    }
                    exit;
                }
            }
        }
        echo "-1";
    }
}

$obj = new main();
$obj->run();