Buggy python submission (verdict: Runtime Error):
from test import set_stdin_sandbox
set_stdin_sandbox()

import itertools
N = int(input())
s = list(map(lambda x: True if x == "o" else False, list(input())))

f = lambda x,y: not(x^y)

def hantei(N,s):
    for onetwo in itertools.product((True, False), (True, False)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                res[n] = f(res[n-2], f(res[n-1], s[n-1]))
        # check s[0]
        if not ((res[1] == res[N-1]) ^ res[0]) == s[0]:
            if not ((res[0] == res[N-2]) ^ res[N-1]) == s[N-1]:
                print(''.join(map(lambda x: "S" if x == True else "W", res.values())))
                return True

    return False

if not hantei(N, s):
    print(-1)

Fixed submission:
import itertools
N = int(input())
s = list(input())

def hantei(N,s):
    for onetwo in itertools.product((0, 1), (0, 1)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                if res[n-1] == 0 and s[n-1] == "o":
                    res[n] = res[n-2]
                elif res[n-1] == 0 and s[n-1] == "x":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "o":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "x":
                    res[n] = res[n-2]
        # check s[0]
        if (res[1] == res[N-1]) and res[0] == 0 and s[0] == "x":
            continue
        if (res[1] == res[N-1]) and res[0] == 1 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 0 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 1 and s[0] == "x":
            continue
        # check s[n-1]
        if (res[0] == res[N-2]) and res[N-1] == 0 and s[N-1] == "x":
            continue
        if (res[0] == res[N-2]) and res[N-1] == 1 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 0 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 1 and s[N-1] == "x":
            continue

        print(''.join(map(lambda x: "S" if x == 0 else "W", res.values())))
        return True

    return False

if not hantei(N, s):
    print(-1)

Buggy python submission (verdict: Runtime Error):
import itertools
N = int(input())
s = list(map(lambda x: True if x == "o" else False, list(input())))

# N = 6
# s = "ooxoox"
# N = 3
# s = "oox"
s = [True, True, False]

def hantei(N,s):
    f = lambda x,y: not(x^y)
    for onetwo in itertools.product((True, False), (True, False)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                res[n] = f(res[n-2], f(res[n-1], s[n-1]))
        # check s[0]
        if not ((res[1] == res[N-1]) ^ res[0]) == s[0]:
            if not ((res[0] == res[N-2]) ^ res[N-1]) == s[N-1]:
                print(''.join(map(lambda x: "S" if x == 0 else "W", res.values())))
                return True

    return False

if not hantei(N, s):
    print(-1)
    


Fixed submission:
import itertools
N = int(input())
s = list(input())

def hantei(N,s):
    for onetwo in itertools.product((0, 1), (0, 1)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                if res[n-1] == 0 and s[n-1] == "o":
                    res[n] = res[n-2]
                elif res[n-1] == 0 and s[n-1] == "x":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "o":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "x":
                    res[n] = res[n-2]
        # check s[0]
        if (res[1] == res[N-1]) and res[0] == 0 and s[0] == "x":
            continue
        if (res[1] == res[N-1]) and res[0] == 1 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 0 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 1 and s[0] == "x":
            continue
        # check s[n-1]
        if (res[0] == res[N-2]) and res[N-1] == 0 and s[N-1] == "x":
            continue
        if (res[0] == res[N-2]) and res[N-1] == 1 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 0 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 1 and s[N-1] == "x":
            continue

        print(''.join(map(lambda x: "S" if x == 0 else "W", res.values())))
        return True

    return False

if not hantei(N, s):
    print(-1)

Buggy python submission (verdict: Runtime Error):
import itertools
N = int(input(l))
s = list(input())

# N = 6
# s = "ooxoox"
N = 3
s = "oox"

def hantei(N,s):
    for onetwo in itertools.product((0, 1), (0, 1)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                if res[n-1] == 0 and s[n-1] == "o":
                    res[n] = res[n-2]
                elif res[n-1] == 0 and s[n-1] == "x":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "o":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "x":
                    res[n] = res[n-2]
        # check s[0]
        if (res[1] == res[N-1]) and res[0] == 0 and s[0] == "x":
            continue
        if (res[1] == res[N-1]) and res[0] == 1 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 0 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 1 and s[0] == "x":
            continue
        # check s[n-1]
        if (res[0] == res[N-2]) and res[N-1] == 0 and s[N-1] == "x":
            continue
        if (res[0] == res[N-2]) and res[N-1] == 1 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 0 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 1 and s[N-1] == "x":
            continue

        print(''.join(map(lambda x: "S" if x == 0 else "W", res.values())))
        return True

    return False

if not hantei(N, s):
    print(-1)

Fixed submission:
import itertools
N = int(input())
s = list(input())

def hantei(N,s):
    for onetwo in itertools.product((0, 1), (0, 1)):
        res = {}
        for n in range(N):
            if n == 0:
                res[n] = onetwo[0]
            elif n == 1:
                res[n] = onetwo[1]
            else:
                if res[n-1] == 0 and s[n-1] == "o":
                    res[n] = res[n-2]
                elif res[n-1] == 0 and s[n-1] == "x":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "o":
                    res[n] = 1 if res[n-2] == 0 else 0
                elif res[n-1] == 1 and s[n-1] == "x":
                    res[n] = res[n-2]
        # check s[0]
        if (res[1] == res[N-1]) and res[0] == 0 and s[0] == "x":
            continue
        if (res[1] == res[N-1]) and res[0] == 1 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 0 and s[0] == "o":
            continue
        if (res[1] != res[N-1]) and res[0] == 1 and s[0] == "x":
            continue
        # check s[n-1]
        if (res[0] == res[N-2]) and res[N-1] == 0 and s[N-1] == "x":
            continue
        if (res[0] == res[N-2]) and res[N-1] == 1 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 0 and s[N-1] == "o":
            continue
        if (res[0] != res[N-2]) and res[N-1] == 1 and s[N-1] == "x":
            continue

        print(''.join(map(lambda x: "S" if x == 0 else "W", res.values())))
        return True

    return False

if not hantei(N, s):
    print(-1)