100%AC

#include<cstdio>
int main(){
    int t;
    scanf("%d\n",&t);
    for(int i=0;i<t;i++){
        int a=0,b=0;char c;
        for(int i=0;i<5;i++){
            scanf("%c",&c);
            if(c=='A')a++;
            else b++;
        }
        printf(a>b?"A\n":"B\n");
        scanf("\n");
    }
}