package main

import (
	"fmt"
	"strings"
)

func main() {
	var s string
	if _, err := fmt.Scan(&s); err != nil {
		return
	}
	var n int
	fmt.Scan(&n)
	
	ans := ""
	for i := 0; i < n; i++ {
		var page string
		fmt.Scan(&page)
		if strings.HasPrefix(page, s) {
			if ans == "" || page < ans {
				ans = page
			}
		}
	}
	
	if ans == "" {
		fmt.Println(s)
	} else {
		fmt.Println(ans)
	}
}