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: Wrong Answer)

using System;

namespace arc069_b
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string s = Console.ReadLine();
            bool[] animals = new bool[n + 1];
            animals[0] = true; animals[1] = true;
            for (int i = 2; i <= n; i++)
            {
                if ((s[(i - 1) % n] == 'o') == (animals[i - 1] == true)) animals[i] = animals[i - 2];
                else animals[i] = !animals[i - 2];
            }
            if (animals[0] == animals[n])
            {
                for (int i = 0; i < n; i++)
                {
                    Console.Write(animals[i] ? 'S' : 'W');
                }
                Console.WriteLine();
            }
            else
            {
                animals[0] = true; animals[1] = false;
                for (int i = 2; i <= n; i++)
                {
                    if ((s[(i - 1) % n] == 'o') == (animals[i - 1] == true)) animals[i] = animals[i - 2];
                    else animals[i] = !animals[i - 2];
                }
                if (animals[0] == animals[n])
                {
                    for (int i = 0; i < n; i++)
                    {
                        Console.Write(animals[i] ? 'S' : 'W');
                    }
                    Console.WriteLine();
                }
                else
                {
                    animals[0] = false; animals[1] = true;
                    for (int i = 2; i <= n; i++)
                    {
                        if ((s[(i - 1) % n] == 'o') == (animals[i - 1] == true)) animals[i] = animals[i - 2];
                        else animals[i] = !animals[i - 2];
                    }
                    if (animals[0] == animals[n])
                    {
                        for (int i = 0; i < n; i++)
                        {
                            Console.Write(animals[i] ? 'S' : 'W');
                        }
                        Console.WriteLine();
                    }
                    else
                    {
                        animals[0] = false; animals[1] = false;
                        for (int i = 2; i <= n; i++)
                        {
                            if ((s[(i - 1) % n] == 'o') == (animals[i - 1] == true)) animals[i] = animals[i - 2];
                            else animals[i] = !animals[i - 2];
                        }
                        if (animals[0] == animals[n])
                        {
                            for (int i = 0; i < n; i++)
                            {
                                Console.Write(animals[i] ? 'S' : 'W');
                            }
                            Console.WriteLine();
                        }
                        else
                        {
                            Console.WriteLine(-1);
                        }
                    }
                }
            }
        }
    }
}