AOJ Volume0 0047 Cup Game

/******************************
*   2012/0516                 *
*   AOJ Volume0 0047 CupGame  *
*   crane                     *
*******************************/

#include<iostream>
#include<string>

int main(){
    int va[]={1, 0, 0};

    std::string input;
    while(getline(std::cin,input) && input.length() != 0){      
        int in1 = input.at(0) - 'A';
        int in2 = input.at(2) - 'A';
        int tmp = va[in1];
        va[in1] = va[in2];
        va[in2] = tmp;
    }

    for(int i=0; i<3; i++)
        if(va[i]==1){
            char res = i + 'A';
            std::cout << res << std::endl;
    }
    return 0;
}