solver.py

from string import ascii_lowercase as u
import string

with open('secret.txt') as f:
	datas = f.read().splitlines()

datas = {
	'plain': datas[0],
	'key': map(lambda x: -int(x), datas[1].split(','))
}

assert len(datas['plain']) == len(datas['key'])

flag, shift = "", lambda x, y: x.lower().translate(string.maketrans(u, u[y:] + u[:y]))
for index, data in enumerate(datas['plain']):
	flag += shift(data, datas['key'][index])

print flag