#include <stdio.h>

int main() {
    char eA, eB;
    float tA, tB;

    scanf("%c %c", &eA, &eB);
    scanf("%f %f", &tA, &tB);

    if (eA == 'F') {
        tA = (tA - 32.0) * 5.0 / 9.0;
    }

    if (eB == 'F') {
        tB = (tB - 32.0) * 5.0 / 9.0;
    }

    if (tA < tB) {
        printf("A\n");
    }
    else {
        printf("B\n");
    }
}