Intermediate · Dictionaries · 139 of 264

Stock count

A shop records deliveries (positive) and sales (negative). Print the final stock of each item, in alphabetical order, leaving out items with 0.

Input: n, then n lines "item amount". Output: one line per item: <item> <stock>

Examples

Input

4
apple 10
pear 5
apple -3
pear -5

Output

apple 7

Input

1
pen 1

Output

pen 1

One more test checks other inputs when you press Check.

Stuck? The idea behind dictionaries

A dictionary links keys to values, like words to meanings: ages["Ann"] = 12. Looking up a key is fast, however big it is.

.get(key, 0) gives a default when the key isn't there; looping over a dictionary gives its keys, .items() gives keys and values together.

counts = {}
for word in input().split():
    counts[word] = counts.get(word, 0) + 1
for word, n in counts.items():
    print(word, n)

Watch for: Reading a key that isn't there stops the program with a KeyError: check with in, or use .get().