#include <stdio.h>

int main() {
    int num;
    scanf("%d", &num);
    switch(num){
        case 100:
            printf("A");
            break;
                
        case 99:
            printf("B");
            break;
        case 98:
            printf("B");
            break;
        case 97:
            printf("B");
            break;
        case 96:
            printf("B");
            break;
        case 95:
            printf("B");
            break;
        case 94:
            printf("B");
            break;
        case 93:
            printf("B");
            break;
        case 92:
            printf("B");
            break;
        case 91:
            printf("B");
            break;
        case 90:
            printf("B");
            break;
    }
}