Problem:
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`.

Incorrect submission (verdict: Wrong Answer):
N=int(input())
S=list(str(input()))
hyp=[["S","S"],["S","W"],["W","S"],["W","W"]]
flag=0
for i in range(4):
    if flag==2:
        break
    flag=0
    ans=[]
    ans.append(hyp[i][0])
    ans.append(hyp[i][1])
    for j in range(1,N+1):
        if j>=N-1:
            if j==N:
                j=0
                t=1
            else:
                t=0
            if ans[j]=="S":
                if S[j]=="o":
                    if ans[j-1]=="S":

                        if ans[t]=="S":
                            flag=+1
                    else:
                        if ans[t]=="W":
                            flag=+1
                else:
                    if ans[j-1]=="S":
                        if ans[t]=="W":
                            flag=+1
                    else:
                        if ans[t]=="S":
                            flag=+1
            else:
                if S[j]=="o":
                    if ans[j-1]=="S":
                        if ans[t]=="W":
                            flag=+1
                    else:
                        if ans[t]=="S":
                            flag=+1
                else:
                    if ans[j-1]=="S":
                        if ans[t]=="S":
                            flag=+1
                    else:
                        if ans[t]=="W":
                            flag=+1
                            
        else:
            if ans[j]=="S":
                if S[j]=="o":
                    if ans[j-1]=="S":
                        ans.append("S")
                    else:
                        ans.append("W")
                else:
                    if ans[j-1]=="S":
                        ans.append("W")
                    else:
                        ans.append("S")
            else:
                if S[j]=="o":
                    if ans[j-1]=="S":
                        ans.append("W")
                    else:
                        ans.append("S")
                else:
                    if ans[j-1]=="S":
                        ans.append("S")
                    else:
                        ans.append("W")

if flag==0:
    print(-1)
else:
    for i in range(len(ans)):
        if i!=len(ans)-1:
            print(ans[i],end="")
        else:
            print(ans[i])

Fixed, accepted submission:
N=int(input())
S=list(str(input()))
hyp=[["S","S"],["S","W"],["W","S"],["W","W"]]
flag=0
for i in range(4):
    if flag==2:
        break
    flag=0
    ans=[]
    ans.append(hyp[i][0])
    ans.append(hyp[i][1])
    for j in range(1,N+1):
        if j>=N-1:
            if j==N:
                j=0
                t=1
            else:
                t=0
            
            if ans[j]=="S":
                if S[j]=="o":
                    if ans[j-1]=="S":
                        if ans[t]=="S":
                            flag+=1
                    else:
                        if ans[t]=="W":
                            flag+=1
                else:
                    if ans[j-1]=="S":
                        if ans[t]=="W":
                            flag+=1
                    else:
                        if ans[t]=="S":
                            flag+=1
            else:
                if S[j]=="o":
                    if ans[j-1]=="S":
                        if ans[t]=="W":
                            flag+=1
                    else:
                        if ans[t]=="S":
                            flag+=1
                else:
                    if ans[j-1]=="S":
                        if ans[t]=="S":
                            flag+=1
                    else:
                        if ans[t]=="W":
                            flag+=1
                            
        else:
            if ans[j]=="S":
                if S[j]=="o":
                    if ans[j-1]=="S":
                        ans.append("S")
                    else:
                        ans.append("W")
                else:
                    if ans[j-1]=="S":
                        ans.append("W")
                    else:
                        ans.append("S")
            else:
                if S[j]=="o":
                    if ans[j-1]=="S":
                        ans.append("W")
                    else:
                        ans.append("S")
                else:
                    if ans[j-1]=="S":
                        ans.append("S")
                    else:
                        ans.append("W")

if flag!=2:
    print(-1)
else:
    for i in range(len(ans)):
        if i!=len(ans)-1:
            print(ans[i],end="")
        else:
            print(ans[i])