Vending Route Restock Tally

A vending-machine operator runs a fleet of machines spread across a city, each identified by a numeric id. Every time a route technician restocks a machine, the visit is logged as one line recording which machine was restocked and how many units were loaded into it during that single visit. A machine may be restocked many times over the log's history, and the log may record visits to many different machines in any order. Given the full restock log, compute the total number of units loaded into each machine across every visit recorded for it.

Input format

• Line 1: an integer n, the number of restock log entries.
• Next n lines: two integers machine_id and units — one visit's machine id and the number of units loaded during that visit.

Output format

For every machine id that appears at least once in the log, print one line "machine_id total_units", where total_units is the sum of units loaded into that machine across all of its visits. Print the lines in ascending order of machine_id.

Constraints

• 1 <= n <= 100000
• 1 <= machine_id <= 10^9
• 1 <= units <= 10^6

5
310 7
101 20
205 15
101 10
205 5

101 30
205 20
310 7

3
42 100
42 250
42 5

42 355