#include <stdio.h>
struct ball{
char *name;
int value;
};
char compare_balls(struct ball b1,struct ball b2,struct ball b3){
// 输出三个中不一样的数字
if (b1.value!=b2.value && b1.value!=b3.value){return *b1.name;}
if (b2.value!=b1.value && b2.value!=b3.value){return *b2.name;}
if (b3.value!=b1.value && b3.value!=b2.value){return *b3.name;}
}
int main(void){
int a,b,c;
struct ball b1,b2,b3;
char r;
if (scanf("%d %d %d",&a,&b,&c)!=0){
b1.name = "A";
b1.value = a;
b2.name = "B";
b2.value = b;
b3.name = "C";
b3.value = c;
r = compare_balls(b1,b2,b3);
printf("%c",r);
}else{
printf("输入数据存在异常");
}
return 0;
}