#!/usr/bin/env python3
"""json-check: Validate and pretty-print JSON files or stdin."""
import json
import sys

def main():
    if len(sys.argv) > 1:
        with open(sys.argv[1], 'r') as f:
            data = json.load(f)
    else:
        data = json.load(sys.stdin)
    
    print(json.dumps(data, indent=2, sort_keys=True))
    return 0

if __name__ == '__main__':
    sys.exit(main())