#include <stdio.h>

void count(int *score, char *grade){
    if(*score >= 90) {
        *grade = 'A';
    } else if (*score >= 80) {
        *grade = 'B';
}
}

int main() {
    int score = 80;
    char grade;

    scanf("%d", &score);

    count(&score, &grade);

    printf("%c", grade);
}