/*
ID: barish21
LANG: C++14
TASK: test
*/

/****Author: Barish Namazov****/
#include <bits/stdc++.h>
#include <iostream>
#include <fstream>
#include <cstdio>
#include <queue>
#include <vector>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <stack>
#include <cstring>
#include <cmath>

using namespace std;

/***TEMPLATE***/
#define intt long long

#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define sz(s) (intt)s.size()

#define ms0(arr) memset(arr,0,sizeof arr)
#define ms63(arr) memset(arr,63,sizeof arr)

#define forn(i,a,b) for(intt i=a;i<=b;i++)
#define rofn(i,a,b) for(intt i=a;i>=b;i--)
#define setf(it,myset) for(set<intt>::iterator it=myset.begin();it!=myset.end();it++)

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define VI vector<intt>
#define PII pair<intt,intt>
#define VPII vector< PII >

#define posl(ch) (int)(ch-'a'+1)
#define posL(ch) (int)(ch-'A'+1)

#define IO ios_base::sync_with_stdio(false);cin.tie();
/***************/

/***Additional Functions***/
intt powmod(intt a,intt b,intt mod){intt res=1;a%=mod;assert(b>=0);for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
intt gcd(intt a,intt b){return __gcd(a, b);}
intt lcm(intt a,intt b){return a*b/gcd(a,b);}
intt is_prime(intt n){if(n==1)return 0;if(n==2)return 1;if(n%2==0)return 0;for(intt i=3;i<=sqrt(n);i+=2)if(n%i==0)return 0;return 1;}
intt is_integer(double n){if(floor(n)==ceil(n))return 1;return 0;}

intt sto_int(string s){stringstream ss(s);intt n;ss>>n;return n;}
string to_string(intt n){stringstream ss;ss<<n;string s=ss.str();return s;}

/**************************/

intt arr[1000001], holes[1000001], bone;
int main()
{
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    //ofstream fout ("test.out");
    //ifstream fin ("test.in");
    IO;
    intt n, m, k;
    cin >> n >> m >> k;
    for (intt i = 1; i <= m; i++) {
        intt t;
        cin >> t;
        holes[t] = 1;
    }
    bone = 1;
    for (intt i = 1; i <= k; i++) {
        intt a, b;
        cin >> a >> b;
        if (holes[bone]) {
            cout << bone << endl;
            return 0;
        }
        if (bone == a)
            bone = b;
            else
        if (bone == b)
            bone = a;
        if (holes[bone]) {
            cout << bone << endl;
            return 0;
        }
        //cout << bone << endl;
    }
    cout << bone << endl;
    return 0;
}