Q9498.java

package forRank;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Q9498 {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		int score = Integer.parseInt(br.readLine());
		char grade = 'F';
		
		if(score >= 90)
			grade = 'A';
		else if(score >= 80)
			grade = 'B';
		else if(score >= 70)
			grade = 'C';
		else if(score >= 60)
			grade = 'D';
		
		bw.write(grade + "\n");
		
		br.close();
		bw.close();
	}
}