import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;

public class Main {
	
	public static String dfs(String part, int pick, int sum, String[] yuki, String[] coder){
		//System.out.println(part + " : " + pick);
		
		if(pick >= sum){ return part; }
		else if(part.length() <= pick){ return null; }
		
		final char pick_ch = part.charAt(pick);
		final String for_next = part.substring(0, pick);
		
		for(final String y : yuki){
			if(y.charAt(0) != pick_ch){ continue; }
			
			final String ret = dfs(for_next + y, pick + 1, sum, yuki, coder);
			if(ret != null){ return ret; }
		}
		
		for(final String c : coder){
			if(c.charAt(0) != pick_ch){ continue; }
			
			final String ret = dfs(for_next + c, pick + 1, sum, yuki, coder);
			if(ret != null){ return ret; }
		}
		
		return dfs(part, pick + 1, sum, yuki, coder);
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		String[] yuki = new String[N];
		for(int i = 0; i < N; i++){ yuki[i] = sc.next(); }
		
		final int M = sc.nextInt();
		String[] coder = new String[M];
		for(int i = 0; i < M; i++){ coder[i] = sc.next(); }
		
		int sum = 0;
		for(final String y : yuki){ sum += y.length(); }
		
		if(N == 1 && M == 1){
			System.out.println(yuki[0].equals(coder[0]) ? yuki[0] : "-1");
			return;
		}
		
		String answer = null;
		for(final String y : yuki){
			if(y.length() == 1){ continue; }
			
			final String ret = dfs(y, 1, sum, yuki, coder);
			if(ret != null){ answer = ret; }
		}
		for(final String c : coder){
			if(c.length() == 1){ continue; }
			
			final String ret = dfs(c, 1, sum, yuki, coder);
			if(ret != null){ answer = ret; }
		}
		
		System.out.println(answer == null ? "-1" : answer);
	}
}