#include <bits/stdc++.h>
using namespace std;

#define INF 100000000000000000

long long N, A, B, i, j, k, a, b, c, w, dist[10010], proc[10010], source, dest;
vector<vector<pair<long long, long long>>> adj;
priority_queue<pair<long long, long long>> q;

int main() {
  ifstream cin("input.txt");
  ofstream cout("output.txt");

  cin >> N >> A >> B;
  source = 1;
  dest = N;
  for (i = 0; i <= A + B; i++) {
    adj.push_back({});
  }
  for (i = 0; i < A; i++) {
    cin >> a >> b;
    adj[a].push_back({b, 0});
    adj[b].push_back({a, 0});
  }
  for (i = 0; i < B; i++) {
    cin >> a >> b;
    adj[a].push_back({b, 1});
    adj[b].push_back({a, 1});
  }

  for (i = 1; i <= N; i++) {
    dist[i] = INF;
    proc[i] = 0;
  }
  dist[source] = 0;
  q.push({0, source});

  while (!q.empty()) {
    a = q.top().second;
    q.pop();
    if (proc[a] == 1) {
      continue;
    }
    proc[a] = 1;
    for (auto u : adj[a]) {
      b = u.first;
      w = u.second;
      if (dist[a] + w < dist[b]) {
        dist[b] = dist[a] + w;
        q.push({-dist[b], b});
      }
    }
  }

  cout << dist[dest];

  return 0;
}