Guess the password

You are given a set of tuples and you need to guess a password from the given input. The tuples need not be of same length. There is only one password possible in the given input. The order of the characters need to be maintained for generating the password. The password will be of maximum 7 characters. The characters in the password are not repeated.

e.g. below

bca
bcd
cad

The password here is 'bcad'.
bcda cannot be the password because the d should occur only after 'a' or 'c'.