문제는 다음과 같습니다.

https://www.acmicpc.net/problem/1924

　
import java.util.Scanner;

public class Test1924{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int x=sc.nextInt();
		int y=sc.nextInt();
		int day=0;
		for(int i=1; i<x; i++){
			if(i==1 || i==3 || i==5 || i==7 || i==8 || i==10 || i==12){
				day+=31;
			}
			if(i==2){
				day+=28;
			}
			if(i==4 || i==6 || i==9 || i==11){
				day+=30;
			}
		}
		
		day+=y;
		int week= day%7;
		switch(week){
			case 0:
				System.out.println("SUN");
				break;
			case 1:
				System.out.println("MON");
				break;
			case 2:
				System.out.println("TUE");
				break;
			case 3:
				System.out.println("WED");
				break;
			case 4:
				System.out.println("THU");
				break;
			case 5:
				System.out.println("FRI");
				break;
			case 6:
				System.out.println("SAT");
				break;
		}
	}
}
　

결과는 다음과 같습니다.