given_string = input()
n = int(input())
n_by_givstring = int(n/len(given_string)) 
extra_string_required = n%len(given_string) 
extra_string = given_string[:extra_string_required]
char_count_in_orig_str = given_string.count('a')
extra_count = extra_string.count('a')
output = n_by_givstring*char_count_in_orig_str 
output+=extra_count
print(output)