var s = "aabaabaa"
for i in 0..len(s):
if s[i] == 'a' and s[i+1] == 'b':
# ``i < len(s)``であるか否かを調べなくても良いのだ!
echo ($i)
dmFyIHMgPSAiYWFiYWFiYWEiCmZvciBpIGluIDAuLmxlbihzKToKICBpZiBzW2ldID09ICdhJyBhbmQgc1tpKzFdID09ICdiJzoKICAgICMgYGBpIDwgbGVuKHMpYGDjgafjgYLjgovjgYvlkKbjgYvjgpLoqr/jgbnjgarjgY/jgabjgoLoia/jgYTjga7jgaDvvIEKICAgIGVjaG8gKCRpKQ==