#include <stdio.h>
int main()
{
    double score;
    while (scanf("%f", &score) != EOF)
    {
        if(score<0 || score>100){
            printf("Error\n");
        }
        else {
            if(score>=90) {
                printf("A+\n");
            }
            else if(score>=80) {
                printf("A\n");
            }
            else if(score>=70){
                printf("B+\n");
            }
            else if(score>=60){
                printf("B\n");
            }
            else {
                printf("C");
            }
        }
    }
    return 0;
}