#!/usr/bin/python

import sys

import yaml

def inputs(args):
    if args:
        for filename in args:
            with open(filename) as f:
                yield filename, f
    else:
        yield '-', sys.stdin

objs = []
for filename, f in inputs(sys.argv[1:]):
    objs.append(yaml.safe_load(f))
yaml.safe_dump_all(objs, stream=sys.stdout, indent=4, default_flow_style=False)