안녕하세요 런타임에러 뜨는 이유좀 알수 있을까요 ??

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

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        HashMap<Character,Integer> map1 = new HashMap<>();
        String str1 = sc.next();
        String str2 = sc.next();
        String answer = "YES";

        for (char i : str1.toCharArray()){
            map1.put(i,map1.getOrDefault(i,0)+1);
        }
        for (char i : str2.toCharArray()){
            if (!map1.containsKey(i)|| map1.get(i)==0) {
                answer="NO";
            }
            map1.put(i,map1.get(i)-1);
        }
        System.out.println(answer);

    }
}