//Послание в main))

#include <iostream>
#include <stdio.h>
#include <cctype>

using std::cout;
using std::endl;
using std::ostream;

class Alpha{
    private:
        unsigned bin;
    public:
        Alpha(){ bin = 0; }
        Alpha(char*);
        Alpha operator +(Alpha&);
        Alpha operator -(Alpha&);
        friend ostream& operator <<(ostream&, Alpha&);
};

Alpha::Alpha(char *s){
    bin = 0;
    while(*s)
    {
        bin |= 1 << (tolower(*s) - 'a');
        s++;
    }
}

Alpha Alpha::operator -(Alpha& y){
    Alpha z;
    z.bin = this->bin & (~y.bin);
    return(z);
}

Alpha Alpha::operator +(Alpha& y){
    Alpha z;
    z.bin = this->bin | y.bin;
    return(z);
}

ostream& operator <<(ostream& out, Alpha& obj){
    unsigned bit = 1;
    int i;
    for(i = 0; i < 26; i++){
        if((obj.bin & bit) > 0)
            out << (char)('a' + i);
        bit = bit << 1;
    }
    return(out);
}

int main(int argc, char *argv[]){
    if(argc < 3)
        return(puts("Usage: ./lab4 <string1> <string2>"));
    Alpha x(argv[1]);
    Alpha y(argv[2]);
    Alpha answer, z, n;
    z = x - y;
    n = y - x;
    answer = z + n;
    //Формула answer = (x - y) + (y - x) не будет работать, да и чует мое сердце, что
    //Будут меняться значения x и y
    cout << answer << endl;
}