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