I've left my solution below in case it helps anyone. I'm not sure if its the best solution, but it worked!

from collections import defaultdict

if name == 'main': n, m = list(map(int, input().split())) d = defaultdict(list)

for _ in range(n):
    d['a'].append(input())


for _ in range(m):
    current = input().strip()
    indices = []
    for i in range(n):
        if current == d['a'][i]:
            index = i + 1
            indices.append(index)     
    if indices:
        print(' '.join(map(str, indices)))
    else:
        print('-1')

Check this: from collections import defaultdict d = defaultdict(list)

n, m = map(int,input().split())

for i in range(1,n+1): d[input()].append(i)

for i in range(m): word_B = input() if word_B in d: print(*d[word_B]) else: print(-1)

I defaulted to not using default dict

if __name__ == "__main__":
    n,m = map(int, input().split(" "))
    a, b = [], []
    for _ in range(n): a.append(input())
    for _ in range(m): b.append(input())
    
    for b_word in b:
        indices = [i+1 for i,word in enumerate(a) if word == b_word]
        print(" ".join(map(str, indices))) if indices else print(-1)

I tried to use defaultdict.

Following is my code:

import sys from collections import defaultdict

if name == 'main': n, m = map(int, input().split()) #input range check if n<0 or n>10000: print("Input from 1 to 10000!!!") sys.exit(-1) elif m<0 or m>100: print("Input from 1 to 100!!!") sys.exit(-1)

#list/defaultdict definition
a_list=[]
b_list=[]
A_indices=defaultdict(list)

#input group A list
for i in range(n):
    word_a=input()
    if len(word_a)<1 or len(word_a)>100:
        print("Input word in length from 1 to 100!!!")
        continue
    else:
        a_list.append(word_a)
        #input A_indices dict with word index according to word
        A_indices[word_a].append(i+1)
        #print(A_indices)   

#input group B list and check words in group A                    
for _ in range(m):
    word_b=input()
    if len(word_b)<1 or len(word_b)>100:
        print("Input word in length from 1 to 100!!!")
        continue

    b_list.append(word_b)

    #check if word exists in group A list by using A_indices defaultdict
    indices = A_indices[word_b]

    #print indices in group A list for word
    if indices:
        print(" ".join(map(str, indices)))
    else:
        print("-1")

i found myself solving this without the need to use defaultdict (but i feel like it's not the most efficient solution):

n , m = map(int, input().split())
A= []
B = []
for i in range(n):
    A.append(input())
    
for i in range(m):
    B.append(input())

found = False
for charB in B:
    for ind,charA in enumerate(A):
        if charB == charA:
            print(ind+1, end=" ")
            found = True

if found:
    print()
    found = False
else:
    print(-1)