package main

import "fmt"

func main() {
	var n, m int
	fmt.Scan(&n, &m)

	set := make(map[int]struct{})
	set[n] = struct{}{}

	for range make([]struct{}, m) {
		for range make([]struct{}, 2) {
			var pq int
			fmt.Scan(&pq)
			if _, ok := set[pq]; ok {
				delete(set, pq)
			} else {
				set[pq] = struct{}{}
			}
		}
	}

	for k, _ := range set {
		fmt.Println(k)
		break
	}
}