Complementary colors are opposite each other on the color wheel and create visual contrast when used together. Using a traditional color wheel, Red and Green are complementary colors, and Blue and Yellow are complementary colors. So, one way of grouping these four colors into two complementary pairs would be: 

- Red and Green
- Blue and Yellow
Red, Blue, Green, Yellow
### Instruction:
How would you group these four colors into two complementary colors?

### Input:
Red, Blue, Green, Yellow

### Response:
