Snake Procession python 3 wrong output

def check(n):

    n=n.lower()


    for i in range(len(n)):

        
       if n[i]=='.':

           
            return check(n[i+1:])

        
        elif n[i]=='t':

            
            return False

        
        elif n=='t' or n=='h':

            
            return False

        else:
            
            k=i+1


            for m in range(k,len(n)):


                if n[m]=='h':
                    

                    return False


                elif n[m]=='t':


                    return check(n[(m+1):])

    return True

for x in range(int(input())):


    p=input()


    s=input()


    if check(s):


        print("Valid")


    else:


        print("Invalid")

can anyone tell me where did i go wrong with this code.
Thanks in advance:-]

here is the problem link:
https://www.codechef.com/problems/SNAKPROC

There-

Input
1
3
H..
Your Output
Valid
Expected Output
Invalid (Missing tail)