#!/usr/bin/env python3

import sys
import click


TISCH = {
    2: ('0b', 'binary'),
    8: ('0', 'octal'),
    10: ('', 'decimal'),
    16: ('0x', 'hexadecimal'),
}


@click.command()
@click.option("-b", '--base', type=click.Choice(['2', '8', '10', '16']), default=16)
@click.argument('d', nargs=-1)
def main(d, base):
    base = int(base)
    prefix, kind = TISCH.pop(base)

    def st(ernal):
        eraction = int(ernal.replace(prefix, ''), base)
        return chr(int(eraction))

    for position, arg in enumerate(d, start=0):
        if not arg.startswith(prefix):
            sys.stderr.write(f'invalid {kind} at argument {position}')
            raise SystemExit(0x53)

    print("".join(map(lambda ate: st(ate), d)))


if __name__ == '__main__':
    main()