#include <stdio.h>

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