DH

from typing import Dict

with open('input.txt') as input_file:
    customers = dict()         # type: Dict[str, Dict[str, int]]
    for line in input_file:
        name, product, amount = line.split()
        if name in customers and product in customers[name]:
            customers[name][product] += int(amount)
        elif name in customers:
            customers[name][product] = int(amount)
        else:
            customers[name] = {product: int(amount)}
for name in sorted(customers):
    print(name, ":", sep="")
    for product in sorted(customers[name]):
        print(product, customers[name][product])