#include <stdio.h>

void get_score(int s);

int main(void) {
  // Initialize variables and get input from stdin
  int score;
  scanf("%d", &score);

	get_score(score);

  return 0;
}

void get_score(int s) {
  if (s > 100) {
    printf("The score is out of range!\n");
  } else if (s >= 90) {
    printf("A\n");
  } else if (s >= 80) {
    printf("B\n");
  } else if (s >= 70) {
    printf("C\n");
  } else if (s >= 60) {
    printf("D\n");
  } else if (s >= 0) {
    printf("E\n");
  } else {
		printf("The score is out of range!\n");
	}
}