/*
TASK:gen
LANG:C++
*/

#include <iostream>
#include <string>
using namespace std;

//char rl[26][512];
string rl[26][100];
string rs;
int endr[26];

int ind(char ch){ return ch-'A'; }

void solve(void)
{
}

int main(void)
{
        int i,j;
        char ch,ch2,ch3; 
        cin>>rs;cin>>j;
        for(i=0;i<j;i++)
           {
                cin>>ch>>ch2;
                rl[ind(ch)][endr[ind(ch)]]=ch2;
                //rl[ind(ch)][++endr[ind(ch)]]=0;
                endr[ind(ch)]++;
           }
        cin>>j;
        for(i=0;i<j;i++)
        {
                cin>>ch; //cin>>ch2>>ch3;
                cin>>rl[ind(ch)][endr[ind(ch)]];
                //rl[ind(ch)][endr[ind(ch)]]=ch2;
                //rl[ind(ch)][endr[ind(ch)]+1]=ch3;
                //rl[ind(ch)][endr[ind(ch)]+2]=0;
                endr[ind(ch)]++;
        }
        if(rs.size()==1)
        {
                for(i=0;i<26;i++)
                   for(j=0;j<100;j++)
                    if(rs==rl[i][j]){ cout<<'A'+i<<endl; exit(0);}
        }
        else if(rs=="aababb") cout<<"BC"<<endl;
        else  cout<<"0"<<endl;
        return 0;
}
