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.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text.RegularExpressions;
using System.Text;
using System.Diagnostics;
using static System.Math;
using static System.Array;

//var input = Console.ReadLine().Split().Select(int.Parse).ToArray();
namespace AtCoderSolve
{

    class Solve
    {
        const int mod = 1000000007;
        const int INF = 2147483647;
        const long SINF = 9223372036854775807;

        static int N;
        static string s;
        
        

        public static void Input()
        {
            var cin = new Scanner();
            N = int.Parse(Console.ReadLine());
            s = Console.ReadLine();
        }

        static void Main(string[] args)
        {
            Input();

            //var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
            //Console.SetOut(sw);

            var ans = new StringBuilder();
            
            for (var j = 0; j < 1 << 2; j++)
            {
                ans.Clear();
                for(var i = 0; i < 2; i++)
                {
                    if ((j & 1 << i) != 0)
                    {
                        ans.Append("W");
                    }
                    else
                    {
                        ans.Append("S");
                    }
                }

                for (var i = 1; i < N; i++)
                {
                    string next;


                    if (s[i] == 'o')
                    {
                        if (ans[i - 1] == 'S')
                        {
                            next = (ans[i] == 'S' ? "S" : "W");
                        }
                        else
                        {
                            next = (ans[i] == 'S' ? "W" : "S");
                        }
                    }
                    else
                    {
                        if (ans[i - 1] == 'S')
                        {
                            next = (ans[i] == 'S' ? "W" : "S");
                        }
                        else
                        {
                            next = (ans[i] == 'S' ? "S" : "W");
                        }
                    }
                    if (i != N - 1) { ans.Append(next); }
                    else
                    {
                        if (next != ans[0].ToString()) { continue; }
                        if (s[0] == 'o')
                        {
                            if (ans[0] == 'S')
                            {
                                if (ans[N - 1] == ans[1])
                                {
                                    Console.WriteLine(ans);
                                    return;
                                }
                            }
                            else
                            {
                                if (ans[N - 1] != ans[1])
                                {
                                    Console.WriteLine(ans);
                                    return;
                                }
                            }
                        }
                        else
                        {
                            if (ans[0] == 'S')
                            {
                                if (ans[N - 1] != ans[1])
                                {
                                    Console.WriteLine(ans);
                                    return;
                                }
                            }
                            else
                            {
                                if (ans[N - 1] == ans[1])
                                {
                                    Console.WriteLine(ans);
                                    return;
                                }
                            }
                        }
                    }
                }
            }

            Console.WriteLine(-1);

            //Console.Out.Flush();

        }





    }

    public class Scanner
    {
        public int[] SplitReader()
        {
            int[] array = Console.ReadLine().Split().Select(int.Parse).ToArray();
            return array;
        }
        public long[] SplitReaderL()
        {
            long[] array = Console.ReadLine().Split().Select(long.Parse).ToArray();
            return array;
        }

    }

    public class Graph
    {
        
    }
}