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;
using System.Linq;

class Program
{
    public static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        string str = Console.ReadLine();
        char[] ans = new char[n + 1];

        str += str[0];

        for (int i = 0; ; i++)
        {
            if (i == 0)
            {
                ans[0] = 'S';
                ans[1] = 'S';
            } else if (i == 1)
            {
                ans[0] = 'S';
                ans[1] = 'W';
            } else if (i == 2)
            {
                ans[0] = 'W';
                ans[1] = 'S';
            } else if (i == 3)
            {
                ans[0] = 'W';
                ans[1] = 'W';
            } else
            {
                ans[0] = 'E';
                break;
            }

            Search(str, ref ans);
            if (ans[0] == ans[n])
            {
                break;
            }
        }

        if (ans[0] == 'E')
        {
            Console.WriteLine("-1");
        } else
        {
            for (int i = 0; i < n; i++)
            {
                Console.Write(ans[i]);
            }
            Console.WriteLine();
        }
    }

    public static void Search(string str, ref char[] ans)
    {
        for (int i = 2; i < str.Length; i++)
        {
            if (ans[i - 1] == 'S')
            {
                if (str[i - 1] == 'o')
                {
                    ans[i] = ans[i - 2];
                } else if (ans[i - 2] == 'W')
                {
                    ans[i] = 'S';
                } else
                {
                    ans[i] = 'W';
                }
            } else
            {
                if (str[i - 1] == 'x')
                {
                    ans[i] = ans[i - 2];
                }
                else if (ans[i - 2] == 'W')
                {
                    ans[i] = 'S';
                }
                else
                {
                    ans[i] = 'W';
                }
            }
        }

        //return ans;
    }
}