The given sentence contains a typo which could be one of the following four types: (1) swapped letters of a word e.g. 'niec' is a typo of the word 'nice'. (2) missing letter in a word e.g. 'nic' is a typo of the word 'nice'. (3) extra letter in a word e.g. 'nicce' is a typo of the word 'nice'. (4) replaced letter in a word e.g 'nicr' is a typo of the word 'nice'. You need to identify the typo in the given sentence. To do this, answer with the word containing the typo.

Ex Input:
Two reen city buses driving down a street next to a sidewalk.

Ex Output:
reen


Ex Input:
a qwhite bowl with some food in it

Ex Output:
qwhite


Ex Input:
A siver commuter train switching train tracks at the station.

Ex Output:

siver