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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;

class E
{
	static void Main()
	{
		var N = int.Parse(Console.ReadLine());
		var S = Console.ReadLine();
		var s = new bool[N];
		for (var i = 0; i < N; i++) s[i] = S[i] == 'o';
		var hoge = new[] { new[] { true, true }, new[] { true, false }, new[] { false, true }, new[] { false, false } };
		var b = new bool[N];
		for (var i = 0; i < 4; i++)
		{
			var answer = Func(hoge[i][0], hoge[i][1], s, N);
			if (answer != "-1")
			{
				Console.WriteLine(answer);
				return;
			}
		}
		Console.WriteLine(-1);
	}
	static string Func(bool r0, bool r1, bool[] s, int N)
	{
		var a = new bool[N];
		a[0] = r0;
		a[1] = r1;
		for (var i = 1; i + 1 < N; i++) a[i + 1] = a[i - 1] == (a[i] == s[i]);
		if ((s[0] == a[0]) == (a[1] == a[N - 1]) && (s[N - 1] == a[N - 1]) == (a[N - 2] == a[0]))
			return string.Join("", a.Select(z => z ? "S" : "W"));
		else return "-1";
	}
}