백준 9498 JAVA

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		
	int a;
	
	Scanner sc = new Scanner(System.in);
	a = sc.nextInt();
	
	if(100>=a && a>=90) {
		System.out.printf("A");
	}
	else if(89>=a && a>=80) {
		System.out.println("B");
	}
	else if (79>=a && a>=70){
		System.out.println("C");
	}
	else if (69>=a && a>=60){
		System.out.println("D");
	}
	else {
		System.out.println("F");
	}
		
		sc.close();
	}

}