animal_dict = {}
ans_dict = {}
ans = []
animal_set = set()
with open('input.txt', 'r') as inp_file:
    for line in inp_file:
        s = line.split()
        animal_set.add(s[1])
        animal_dict[s[0]] = s[1]
for elem in animal_set:
    for k,v in animal_dict.items():
        if v == elem:
            ans.append(k)
    ans_dict[elem] = ans
    ans = []
for k,v in sorted(ans_dict.items(), key=lambda item: len(item[0])):
    print(k+":", ', '.join(sorted(v)))