#include <iostream>
using namespace std;

int main() 
{
  long long int a,b,c;
  long long int d,e,f;
  while(cin>>a>>b>>c){
    if(a>=b&&b>=c) {d=a;e=b;f=c;} 
    else if(a>=c&&c>=b){d=a;e=c;f=b;}
    else if(b>=a&&a>=c){d=b;e=a;f=c;}
    else if(b>=c&&c>=a){d=b;e=c;f=a;}
    else if(c>=a&&a>=b){d=c;e=a;f=b;}
    else {d=c;e=b;f=a;}
    
    if(d>(e+f)){
      if(a==d){cout<<"A"<<endl;}
      else if(b==d){cout<<"B"<<endl;}
      else{cout<<"C"<<endl;}
    }
    else if(d<(e+f)){
      if(a==e){cout<<"A"<<endl;}
      else if(b==e){cout<<"B"<<endl;}
      else{cout<<"C"<<endl;}
    }
  }
    return 0;
}