단어공부

string = input()
string = string.upper()
dict_data = {}
 
for i in range(len(string)) :
  if string[i] in dict_data :
    dict_data[string[i]] += 1
  else :
    dict_data[string[i]] = 1
 
values = list(dict_data.values())
keys = list(dict_data.keys())
max_value = max(values)
 
index = 0
count = 0
ans = ""
for i in range(len(values)) :
  if values[i] == max_value :
    count += 1
    index = i
 
  if count > 1 :
    ans = "?"
    break
 
if ans != "?" :
  ans = keys[index]
 
print(ans)

word = input().upper()
word_list = list(set(word))
cnt = []
 
for i in word_list:
    count = word.count(i)
    cnt.append(count)
if cnt.count(max(cnt)) > 1:
    print('?')
else:
    print(word_list[(cnt.index(max(cnt)))])