Generate a 4-digit password based on the following criteria:
Must contain at least one number, one uppercase letter, one lowercase letter, and one special character.
Your password is `U2b#`
Complete the following task based on the instruction and optional input provided.### Instruction:
Generate a 4-digit password based on the following criteria:

### Input:
Must contain at least one number, one uppercase letter, one lowercase letter, and one special character.

### Output:
Your password is `U2b#`