#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
using lint=long long;
using lubl=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint alpha=26;
    std::vector<lint>ckd(alpha);
    std::vector<lint>next(alpha,-1);
    lint n;std::cin>>n;
    while(n--){
        std::string s;std::cin>>s;
        ckd.at(s.front()-'A')++;
        lint k=s.length();
        for(lint i=0;i<k-1;i++){
            next.at(s.at(i)-'A')=s.at(i+1)-'A';
        }
    }
    std::cin>>n;
    while(n--){
        std::string s;std::cin>>s;
        ckd.at(s.front()-'A')++;
        lint k=s.length();
        for(lint i=0;i<k-1;i++){
            next.at(s.at(i)-'A')=s.at(i+1)-'A';
        }
    }
    if(1u<std::count(ALL(ckd),2ll)){
        std::cout<<-1<<'\n';
        return 0;
    }
    lint i=std::find(ALL(ckd),2ll)-ckd.begin();
    std::cout<<(char)('A'+i);
    while(true){
        if(next.at(i)==-1)break;
        i=next.at(i);
        std::cout<<(char)('A'+i);
    }
    std::cout<<'\n';
}