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 Python (3.4.3) (judge verdict: Accepted)

from collections import defaultdict


def solve(s, l):

    for i in range(1, len(s) - 1):
        # ひつじ
        if l[i] == 1:
            if s[i] == "o":
                l[i + 1] = l[i - 1]
            else:
                l[i + 1] = -1 * l[i - 1]
        # おおかみ
        else:
            if s[i] == "o":
                l[i + 1] = -1 * l[i - 1]
            else:
                l[i + 1] = l[i - 1]

    if l[0] == 1:
        if s[0] == "o":
            ok1 = l[1] == l[-1]
        else:
            ok1 = l[1] != l[-1]
    # おおかみ
    else:
        if s[0] == "o":
            ok1 = l[1] != l[-1]
        else:
            ok1 = l[1] == l[-1]

    if l[-1] == 1:
        if s[-1] == "o":
            ok2 = l[0] == l[-2]
        else:
            ok2 = l[0] != l[-2]
    # おおかみ
    else:
        if s[-1] == "o":
            ok2 = l[0] != l[-2]
        else:
            ok2 = l[0] == l[-2]

    return ok1 and ok2

def main():
    N = int(input())
    S = input()
    ans = [None] * N
    ans[0] = 1
    ans[1] = 1
    if solve(S, ans):
        print(*["S" if x == 1 else "W" for x in ans], sep="")
        return

    ans = [None] * N
    ans[0] = 1
    ans[1] = -1
    if solve(S, ans):
        print(*["S" if x == 1 else "W" for x in ans], sep="")
        return

    ans = [None] * N
    ans[0] = -1
    ans[1] = 1
    if solve(S, ans):
        print(*["S" if x == 1 else "W" for x in ans], sep="")
        return

    ans = [None] * N
    ans[0] = -1
    ans[1] = -1
    if solve(S, ans):
        print(*["S" if x == 1 else "W" for x in ans], sep="")
        return

    print(-1)


if __name__ == '__main__':
    main()