#include <bits/stdc++.h>
using namespace std;
template <typename T>
T maxm(T a, T b) {
  return (a > b) ? a : b;
}
template <typename T>
T minm(T a, T b) {
  return (a < b) ? a : b;
}
template <typename T>
T power(T e, T n) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = x * p;
    p = p * p;
    n >>= 1;
  }
  return x;
}
template <typename T>
T powerm(T e, T n, T m) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = (x * p) % m;
    p = (p * p) % m;
    n >>= 1;
  }
  return x;
}
template <typename T>
T InverseEuler(T a, T m) {
  return (a == 1 ? 1 : powerm(a, m - 2, m));
}
template <typename T>
T lcm(T a, T b) {
  return (a * (b / __gcd(a, b)));
}
template <typename T>
void outPrecision(T a) {
  std::cout << fixed << setprecision(8) << a;
}
string StringToUpper(string strToConvert) {
  std::transform(strToConvert.begin(), strToConvert.end(), strToConvert.begin(),
                 ::toupper);
  return strToConvert;
}
string StringToLower(string strToConvert) {
  std::transform(strToConvert.begin(), strToConvert.end(), strToConvert.begin(),
                 ::tolower);
  return strToConvert;
}
long long MAX = (long long)(3 * 1e18);
long long MOD = (long long)(1e9 + 7);
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  long long n, m, k;
  cin >> n >> m >> k;
  int x;
  map<int, int> isHole;
  for (long long i = (0); i < (m); ++i) {
    cin >> x;
    isHole[x] = true;
  }
  int pos = 1, a, b;
  for (long long i = (0); i < (k); ++i) {
    cin >> a >> b;
    if (a == pos) {
      if (isHole[a]) {
      } else {
        pos = b;
      }
    } else if (b == pos) {
      if (isHole[b]) {
      } else {
        pos = a;
      }
    }
  }
  std::cout << pos << "\n";
  return 0;
}
