#include <stdio.h>

int main(void) {
	// your code goes here
    int score;
    printf("input score:");
    scanf("%d",&score);
    if(90<=score<=100) printf("A");
    else if(80<=score<90) printf("B");
    else if(70<=score<80) printf("C");
    else if(60<=score<70) printf("D");
    else if(0<=score<60) printf("E");
	return 0;
}