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 Kotlin (1.0.0) (judge verdict: Accepted)


fun main(args: Array<String>){
    val n = readLine()!!.toInt()
    val s = readLine()!!

    fun check(ss: String): String? {
        var builder = StringBuilder(ss)
        for (i in 1 until n){
            if(s[i] == 'o' && builder[i] == 'S' || builder[i] == 'W' && s[i] == 'x'){
                builder.append(builder[i-1])
            }else{
                builder.append(if(builder[i-1] == 'S') 'W' else 'S')
            }
        }
        if(builder.first() != builder.last()){
            return null
        }else{
            builder.deleteCharAt(builder.length-1)
        }
        if((s[0] == 'o' && builder[0] == 'S' || s[0] == 'x' && builder[0] == 'W') && builder.last() == builder[1]){
            return builder.toString()
        }
        if((s[0] == 'x' && builder[0] == 'S' || s[0] == 'o' && builder[0] == 'W') && builder.last() != builder[1]){
            return builder.toString()
        }
        return null
    }

    println(check("SS") ?: check("SW") ?: check("WS") ?: check("WW") ?: -1)
}