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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;

class Main{
	public static void main(String[] $){
		//入力
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String s = sc.next();
		sc.close();

		//処理
		//String[] pat = {"SS", "SW", "WS", "WW"};
		boolean[] bs = new boolean[s.length()];
		for(int i = 0; i < s.length(); i++){bs[i] = s.charAt(i) == 'o';}
		boolean[][] pat = {{true,true}, {true,false}, {false,true}, {false,false}};
		for(boolean[] mat : pat){
			ArrayList<Boolean> ans = new ArrayList<>();
			ans.add(mat[0]);ans.add(mat[1]);
			for(int i = 1; i < n-1; i++){
				ans.add((ans.get(i) == ans.get(i-1)) == bs[i]);
			}

			boolean ok = (ans.get(0) == bs[0]) == (ans.get(n-1) == ans.get(1)) && (ans.get(n-1) == bs[n-1]) == (ans.get(n-2) == ans.get(0));
			if(ok){
				for(int i = 0; i < n; i++){
					if(ans.get(i)) System.out.print('S');
					else System.out.print('W');
				}
				System.out.println();
				return;
			}
		}

		//出力
		System.out.println(-1);
	}
}