import java.util.Scanner;

class no570{
	public static void main(String[] agrs) {
		Scanner stdIn=new Scanner(System.in);
		String[] h= {"A","B","C"};
		short[] ha=new short[3];
		short[] hb=new short[3];
		for(short i=0;i<3;i++) {
			ha[i]=stdIn.nextShort();
			hb[i]=ha[i];
		}
		for(short i=0;i<2;i++) {
			short tmp;
			for(short j=0;j<2;j++) {
				if(ha[j]<ha[j+1]) {
					tmp=ha[j];
					ha[j]=ha[j+1];
					ha[j+1]=tmp;
				}
			}
		}
		for(short i=0;i<3;i++) {
			for(short j=0;j<3;j++) if(ha[i]==hb[j]) System.out.println(h[j]);
		}
	}
}