能来位大神帮忙看看吗？我快麻了

with open('trans.in') as f:
    s = f.readline()
num = []
n = ''
for i in s:
    if i.isnumeric():
        n += i
    else:
        if n:
            num.append(n)
        n = ''
if n:
    num.append(n)
with open('train.out', 'a+') as f:
    f.write(str(len(num))+'\n')
    f.write(' '.join(num)+'\n')