#include <stdio.h>
int main()
{
	int h1, w1, h2, w2, h3, w3;
	scanf("%d%d\n%d%d\n%d%d",&h1,&w1,&h2,&w2,&h3,&w3);
	h1=h1-w1;
	h2=h2-w2;
	h3=h3-w3;

	for (int i = 3;i--;) {
		if (h1 > h2 && h1 > h3) {
			puts("A");
			h1 = -1;
		}
		if (h2 > h1 && h2 > h3) {
			puts("B");
			h2 = -1;
		}
		if (h3 > h1 && h3 > h2) {
			puts("C");
			h3 = -1;
		}
	}
}