Total Inventory Query

You are given a list of shipment records and a query. Each shipment record consists of a date, a product ID, and a quantity. The query contains a product ID and a date. Your task is to compute the total quantity of the specified product in the inventory up to and including the given date.

More formally, if you are given shipments as a 2D array where each element is [date, product_id, quantity] and a query [P, D], you need to compute the sum

\( \text{Total} = \sum_{\substack{(d, p, q) \in shipments \\ p = P \; \text{and} \; d \leq D}} q \)

If there are no shipments meeting the condition, the result is 0.

inputFormat

The input is read from standard input (STDIN) in the following format:

• The first line contains an integer n (the number of shipment records).
• The next n lines each contain three space-separated integers: date, product_id, and quantity.
• The last line contains two space-separated integers representing the query: first the product_id to query, then the date.

Note: If n = 0, there will be no shipment lines, but the query line will still be provided.

outputFormat

Output to standard output (STDOUT) a single integer: the total quantity of the specified product in the inventory at the given date.

4
1 0 5
2 0 15
3 1 7
5 0 10
0 4

20