Determine the longest word in the following sentence.
It is a wonderful sunny day.
The longest word in the sentence "It is a wonderful sunny day." is "wonderful" which contains 9 letters.
Complete the following task based on the instruction and optional input provided.### Instruction:
Determine the longest word in the following sentence.

### Input:
It is a wonderful sunny day.

### Output:
The longest word in the sentence "It is a wonderful sunny day." is "wonderful" which contains 9 letters.