Problem:
Map: Delete

For a dictionary $M$ that stores elements formed by a pair of a string key and an integer value, perform a sequence of the following operations. Note that each key in $M$ must be unique.

insert($key$, $x$): Insert an element formed by a pair of $key$ and $x$ to $M$.

get($key$): Print the value with the specified $key$. Print 0 if there is no such element.

delete($key$): Delete the element with the specified $key$.

Input

The input is given in the following format.

$q$
$query_1$
$query_2$
:
$query_q$

Each query $query_i$ is given by

0 $key$ $x$

or

1 $key$

or

2 $key$

where the first digits 0, 1 and 2 represent insert, get and delete operations respectively.

Output

For each get operation, print an integer in a line.

Constraints

$1 \leq q \leq 200,000$

$1 \leq x \leq 1,000,000,000$

$1 \leq $ length of $key$ $ \leq 20$

$key$ consits of lower case letters

Sample Input 1

8
0 blue 4
0 red 1
0 white 5
1 red
1 blue
2 red
1 black
1 red

Sample Output 1

1
4
0
0

Solution in JAVA (judge verdict: Accepted)

import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int q = sc.nextInt();
		Map<String, Integer> map = new HashMap<>();

		for(int i = 0; i < q; i++) {
			int query = sc.nextInt();
			String key = sc.next();

			if(query == 0) {  //insert
				int x = sc.nextInt();
				map.put(key, x);
			}
			else if(query == 1){  //get
				System.out.println(map.getOrDefault(key, 0));
			}
			else map.remove(key);
		}
	}

}