#include"stdio.h"
int main()
{
    char grade;
    double score;
    int temp;
    scanf("%lf",&score);
    temp=(int)score/10;
    switch(temp)
    {
        case 10:
        case 9:
            grade=‘A‘;break;
        case 8:
            grade=‘B‘;break;
        case 7:
            grade=‘C‘;break;
        case 6:
            grade=‘D‘;break;
        default:
            grade=‘E‘;break;
    }
    printf("%c\n",grade);
    return 0;
}