#include <bits/stdc++.h>
using namespace  std;
int gcd(int a,int b)
{
    return b==0?a:gcd(b,a%b);
}
int main()
{
    int x,y,z;
    while(cin>>x>>y>>z)
    {
        if(abs(y-x)>=abs(z-x))
        {
            cout<<"B"<<endl;
        }
        else cout<<"A"<<endl;
    }
}
