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.

Q: Four giraffes walk across the savannah with trees in the backgroud.

A: backgroud.
****
Q: A person walking on the beach with a surfborad

A: surfborad
****
Q: Two oplanes performing an aerial stunt in mid air.

A:
oplanes
****