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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::Write;
macro_rules! eprintln (
    ($($arg:tt)*) => { {
        writeln!(&mut ::std::io::stderr(), $($arg)*);
    } }
);

macro_rules! eprint (
    ($($arg:tt)*) => { {
        write!(&mut ::std::io::stderr(), $($arg)*);
    } }
);

#[allow(unused_macros)]
macro_rules! debug {
    ($($arg:tt)*) => (if cfg!(debug_assertions) {eprint!("[DEBUG] "); eprintln!($($arg)*)});
}

fn main() {
    let mut rd = reader::Reader::new();

    let n: usize = rd.next();
    let s: String = rd.next();
    let mut s = s.chars().collect::<Vec<char>>();
    let c = s[0];
    s.push(c);
//    debug!("{}", s.iter().collect::<String>());

    for a in vec![true, false] {
        for b in vec![true, false] {
            let mut t: Vec<bool> = vec![a, b];
            for i in 1..n + 1 {
                let x = (s[i] == 'o') ^ t[i] ^ t[i - 1];
                t.push(x);
            }
            if t[0] == t[n] && t[1] == t[n + 1] {
                t.truncate(n);
                let ans = t.into_iter().map(|b| if b { 'S' } else { 'W' }).collect::<String>();
                println!("{}", ans);
                return;
            }
        }
    }
    println!("-1");
}

mod reader {
    use std::fmt::Debug;
    use std::str::FromStr;
    use std::collections::VecDeque;
    use std::io::{self, Read};

    fn _read_line() -> String {
        let mut buf = String::new();
        let _ = io::stdin().read_to_string(&mut buf);
        buf
    }

    fn _read_vec_deque_string() -> VecDeque<String> {
        _read_line()
            .split_whitespace()
            .map(|s| s.to_string())
            .collect()
    }

    #[allow(dead_code)]
    pub struct Reader {
        buf: VecDeque<String>,
    }

    #[allow(dead_code)]
    impl Reader {
        pub fn new() -> Reader {
            Reader { buf: VecDeque::new() }
        }

        fn update_buf(&mut self) {
            if self.buf.is_empty() {
                self.buf = _read_vec_deque_string();
            }
        }

        pub fn next<T>(&mut self) -> T
            where
                T: FromStr,
                T::Err: Debug,
        {
            self.update_buf();
            self.buf.pop_front().unwrap().parse::<T>().unwrap()
        }

        pub fn next_n<T>(&mut self, n: usize) -> Vec<T>
            where
                T: FromStr,
                T::Err: Debug,
        {
            let mut vec: Vec<T> = Vec::with_capacity(n);

            for _ in 0..n {
                vec.push(self.next());
            }
            vec
        }
    }
}