package main

import (
	"fmt"
	"sort"
)

type student struct {
	id   int
	name string
	bad  bool
}

type sts []student

func (s sts) Len() int {
	return len(s)
}
func (s sts) Less(i, j int) bool {
	return s[i].id < s[j].id
}
func (s sts) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

func main() {
	var N int
	fmt.Scan(&N)
	students := make(map[string]student, 0)
	for i := 0; i < N; i++ {
		sta := new(student)
		stb := new(student)
		fmt.Scan(&sta.name, &stb.name)
		if v, ok := students[sta.name]; !ok {
			sta.id = i
			sta.bad = true
			students[sta.name] = *sta
		} else {
			v.bad = true
			students[sta.name] = v
		}
		if _, ok := students[stb.name]; !ok {
			stb.id = i
			students[stb.name] = *stb
		}
	}
	a := make([]student, 0)
	for _, v := range students {
		if !v.bad {
			a = append(a, v)
		}
	}
	sort.Sort(sts(a))
	for i := range a {
		fmt.Println(a[i].name)
	}
}