#include <iostream>
using namespace std ;
int main() {
unsigned int a,b,c;
while(cin>>a>>b>>c){
if (a>b+c || (c>a && a>b && a+b>c) || (b>a && a>c && a+c>b))
cout<<"A\n";
else if (b>a+c || (c>b && b>a && b+a>c) || (a>b && b>c && b+c>a))
cout<<"B\n";
else
cout<<"C\n";
}
return 0;
}