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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php

$n = (int)trim(fgets(STDIN));
$s = trim(fgets(STDIN));



$animal = ['S','W'];

for ($i=0; $i < 2; $i++) { 
	for ($j=0; $j < 2; $j++) { 
		$t = $animal[$i] . $animal[$j];
		for ($k=1; $k < $n; $k++) { 
			$tmp_str = $s[$k];
			$tmp_anm = $t[$k];
			if ($tmp_anm === 'S') {
				if ($tmp_str === 'o') {
					$t .= $t[$k-1];
				}else{
					$t .= not($t[$k-1]);
				}
			}else{
				if ($tmp_str === 'o') {
					$t .= not($t[$k-1]);
				}else{
					$t .= $t[$k-1];
				}
			}
		}
		$start_str = $s[0];
		$start_anm = $t[0];
		if ($start_anm === $t[$n]) {
			if ($start_anm === 'S') {
				if($start_str === 'o' && $t[$n-1] === $t[1] || $start_str === 'x' && $t[$n-1] !== $t[1]){
					echo substr($t, 0, $n);
					exit(0);
				}
			}else{
				if($start_str === 'o' && $t[$n-1] !== $t[1] || $start_str === 'x' && $t[$n-1] === $t[1]){
					echo substr($t, 0, $n);
					exit(0);
				}
			}
		}
	}
}
echo '-1';

function not($str){
	if ($str === 'S') {
		return 'W';
	}
	return 'S';
}