#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int INF=2147483647;
int inf=-2147483648;
int mod=1000000007;
#define read(x) cin >> x;
#define fo(i,n) for(i=0;i<n;i++)
#define one(x) cout<<(x)<<endl;
#define two(a,b) cout<<(a)<<" "<<(b)<<endl;
#define three(a,b,c) cout<<(a)<<" "<<(b)<<" "<<(c)<<endl;
#define four(a,b,c,d) cout<<(a)<<" "<<(b)<<" "<<(c)<<" "<<(d)<<endl;
#define write(a,i) cout << a[i] << " ";
int main()
{
    int n,m,k,i,uk=1,q,a,b,f=0;
    cin >> n >> m >> k;int sos[n];fill(sos,sos+n+1,0);
    fo(i,m)
     {
         cin >> q; sos[q]++;
         if (q==1) f=1;
     }
     fo(i,k)
     {
         cin >> a >> b;
         if (a==uk)
         if (f!=1)
         if (sos[b]>0) { uk=b;f=1;}
         else
            uk=b;
         //   cout << a << " " << b << " " << uk << " " << f << endl;
     }
     cout << uk;
    return 0;
}