#include <bits/stdc++.h>
using namespace std;
class union_find {
 public:
  vector<int> arr;
  union_find(int n) {
    arr.resize(n);
    fill(arr.begin(), arr.end(), -1);
  }
  int find(int x) { return arr[x] < 0 ? x : arr[x] = find(arr[x]); }
  void unite(int x, int y) {
    x = find(x), y = find(y);
    if (x == y) return;
    if (arr[x] > arr[y]) swap(x, y);
    arr[x] += arr[y];
    arr[y] = x;
  }
  bool connected(int x, int y) { return find(x) == find(y); }
  int size(int x) { return -arr[find(x)]; }
};
template <typename T>
vector<int> coordinate_compression(const T &a, int cur = 0) {
  int n = a.size();
  T b = a;
  sort(b.begin(), b.end());
  b.erase(unique(b.begin(), b.end()), b.end());
  vector<int> res(n);
  for (int i = 0; i < n; i++)
    res[i] = lower_bound(b.begin(), b.end(), a[i]) - b.begin() + cur;
  return res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  vector<long long> a(2 * n);
  for (int i = 0; i < a.size(); i++) cin >> a[i];
  vector<int> b = coordinate_compression(a);
  union_find uf(2 * n);
  vector<int> mx0(2 * n), mx1(2 * n, -1);
  for (int i = 0; i < 2 * n; i++) mx0[i] = i;
  vector<bool> ju(2 * n);
  for (int i = 0; i < n; i++) {
    int u = b[2 * i], v = b[2 * i + 1];
    if (uf.connected(u, v)) {
      if (ju[uf.find(u)]) {
        cout << -1 << "\n";
        return 0;
      }
      ju[uf.find(u)] = true;
    } else {
      int ru = uf.find(u), rv = uf.find(v);
      uf.unite(u, v);
      mx1[uf.find(u)] = max(max(mx1[ru], mx1[rv]), min(mx0[ru], mx0[rv]));
      mx0[uf.find(u)] = max(mx0[ru], mx0[rv]);
    }
  }
  int res = 0;
  for (int i = 0; i < 2 * n; i++) {
    if (ju[uf.find(i)]) {
      res = max(res, mx0[uf.find(i)]);
    } else {
      res = max(res, mx1[uf.find(i)]);
    }
  }
  for (int i = 0; i < 2 * n; i++) {
    if (res == b[i]) {
      cout << a[i] << "\n";
      return 0;
    }
  }
  return 0;
}
