#include<stdio.h>
#include<iostream>
#include<math.h>
#include<stdlib.h>
#include<string.h>

using namespace std;

class Bykvi{
private:
    unsigned alfabet;
public:
    Bykvi(){ alfabet=0; };
    Bykvi(char *);
    Bykvi operator*(Bykvi&);
    Bykvi operator~();
    operator char*();
    friend ostream& operator<<(ostream&,Bykvi&);
};

Bykvi Bykvi::operator*(Bykvi &p_b){
    Bykvi a;
    a.alfabet=alfabet&(p_b.alfabet);
    return(a);
}

Bykvi Bykvi::operator~(){
    Bykvi a;
    a.alfabet=~alfabet;
    return(a);
}

Bykvi::Bykvi(char *stroka){
    alfabet=0;
    while(*stroka){
        alfabet|=(1<<(tolower(*stroka)-'a'));
        stroka++;
    }
}

ostream& operator<<(ostream& out, Bykvi& a){
    unsigned bit=1;
    int i;
    for(i=0;i<26;i++){
        if(((a.alfabet)&bit)>0)
            out<<(char)('a'+i);
        else
            out<<" ";
        bit=bit*2;
    }
    return(out);
}

int main(int argc,char *argv[]){
    int i,j,k;
    Bykvi a,b;
    Bykvi **p;
    Bykvi itog("abcdefghijklmnopqrstuvwxyz");

    if(argc<2) return 0;
    p=new Bykvi*[argc-1];
    for(i=0;i<(argc-1);i++)
        p[i]=new Bykvi(argv[i]);

    cout<<itog<<endl;

    for(i=1;i<(argc-1);i++)
        for(j=i+1;j<(argc-1);j++){
            a=(*p[i])*(*p[j]);
            a=~a;
            itog=itog*a;
        }

    /*
    for(i=1;i<(argc-1);i++)
        for(j=i+1;j<(argc-1);j++){
            a=Bykvi(argv[i]);
            b=Bykvi(argv[j]);
            a=a*b;
            a=~a;
            itog=itog*a;
  //          cout<<itog<<endl;
        }
    */
    cout<<itog<<endl;

    for(i=0;i<(argc-1);i++)
        delete p[i];
    delete []p;

    return 0;
}