AC代码

text = input()
last_word = ''
n = 0
t = ''
for i in text:
    if last_word == '':
        last_word = i
        n += 1
        continue
    else:
        if i == last_word:
            n += 1
        else:
            t = t + str(n) + last_word
            last_word = i
            n = 1
t = t + str(n) + last_word
print(t)