#include <stdio.h>

int main() { int s,x; scanf("%d",&s); if(s==100){printf("A"); //TODO } else { x=s/10; switch (x){ case 9: printf("A"); break; case 8: printf("B"); break; case 7: printf("C"); break; case 6: printf("D"); break; case 5: case 4: case 3: case 2: case 1: case 0: printf("E"); break; default: printf("EORR"); break; } } return 0;

}