include<stdio.h>

int main(){ int n; scanf("%d",&n); if(90<=n&&n<=100){ printf("A"); } if(80<=n&&n<90){ printf("B"); } if(70<=n&&n<80){ printf("C"); } if(60<=n&&n<70){ printf("D"); } if(0<=n&&n<60){ printf("E"); } return 0; }