#!/usr/bin/env python3

def prompt_list(prompt):
    print(prompt)
    print("(Enter each list item on a separate line. Press Ctrl+D or enter a blank line to finish.)")
    items = []
    try:
        while True:
            inp = input().strip()
            if inp == "": return items
            items.append(inp)
    except EOFError:
        return items

def tag(t, lst):
    return [ (x, t) for x in lst ]

lists = [ f"Shopping list {i + 1}" for i in range(4) ]
items = []
for list_name in lists:
    items.extend(tag(list_name, prompt_list(list_name + ": ")))

item_counts = {}
for item, _ in items:
    item_counts[item] = item_counts.get(item, 0) + 1

# find all items appearing in only 1 list
unique_items = [ (item, tag) for item, tag in items if item_counts[item] == 1 ]
for list_name in lists:
    print(f"{list_name}'s unique items:")
    print("\n".join([ item for item, tag in unique_items if tag == list_name ]))

print("Top items:")
for top_item, count in sorted(item_counts.items(), key=lambda item_pair: item_pair[1], reverse=True)[:3]:
    print(f"{top_item}: {count}")