A+B

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
        int value1 = scanner.nextInt();
        int value2 = scanner.nextInt();

        int answer = value1 + value2;

        System.out.println(answer);
    }
}

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핵심

백준사이트는 입력 값은 Scanner로 받는다.