Sort the list of musical instruments into three distinct categories.
Guitar, Piano, Flute, Violin, Clarinet, Harp
Category 1 - String instruments: 
- Guitar, Violin, Harp

Category 2 - Keyboard instrument: 
- Piano 

Category 3 - Woodwind instruments: 
- Flute, Clarinet
Complete the following task based on the instruction and optional input provided.### Instruction:
Sort the list of musical instruments into three distinct categories.

### Input:
Guitar, Piano, Flute, Violin, Clarinet, Harp

### Output:
Category 1 - String instruments: 
- Guitar, Violin, Harp

Category 2 - Keyboard instrument: 
- Piano 

Category 3 - Woodwind instruments: 
- Flute, Clarinet