#!/usr/bin/env python

# Collapses multimap entries in a spreadsheet dictionary.

# A multimap entry is any input with multiple outputs.

# Collapsed entries will have the form ?alt0,alt1,...

# CSVs without a header are supported.

from collections import OrderedDict

import csv

import sys

def main():

    # Read dict

    dict_ = OrderedDict()

    reader = csv.reader(sys.stdin)

    for row in reader: dict_.setdefault(row[0], []).append(row[1])

    # Write modified dict

    writer = csv.writer(sys.stdout)

    for in_, out in dict_.iteritems():

        out_prefix = ''

        if len(out) > 1: out_prefix = '?'

        writer.writerow([in_, out_prefix+(','.join(out))])

main()