#include <bits/stdc++.h>
using namespace std;
const int N = 2e6 + 100, M = 1e6 + 100;
int n, up[N], down[M], nei[M][2];
int lim;
bool mark[M], bad[M];
vector<int> vec;
int f(int a) { return lower_bound(vec.begin(), vec.end(), a) - vec.begin(); }
bool dfs(int v) {
  mark[v] = true;
  for (int i = 0; i < 2 && nei[v][i] <= lim; i++) {
    int u = nei[v][i];
    if (up[u] == -1 || (mark[up[u]] == false && dfs(up[u]))) {
      up[u] = v;
      down[v] = u;
      return true;
    }
  }
  return false;
}
bool ok(int X) {
  lim = X;
  fill(up, up + N, -1);
  fill(down, down + M, -1);
  memset(bad, false, sizeof bad);
  int matching = 0;
  bool done = false;
  for (int v = 0; v < n; v++)
    if (nei[v][0] > lim)
      return false;
    else if (nei[v][1] > lim) {
      if (up[nei[v][0]] != -1) return false;
      down[v] = nei[v][0];
      up[nei[v][0]] = v;
      bad[v] = true;
      matching++;
    }
  while (done == false) {
    done = true;
    copy(bad, bad + n, mark);
    for (int v = 0; v < n; v++)
      if (mark[v] == false && down[v] == -1 && dfs(v)) {
        matching++;
        done = false;
      }
  }
  return matching == n;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> nei[i][0] >> nei[i][1];
    vec.push_back(nei[i][0]);
    vec.push_back(nei[i][1]);
  }
  sort(vec.begin(), vec.end());
  vec.resize(unique(vec.begin(), vec.end()) - vec.begin());
  for (int i = 0; i < n; i++)
    nei[i][0] = f(nei[i][0]), nei[i][1] = f(nei[i][1]);
  if (ok(vec.size() - 1) == false) {
    cout << -1;
    return 0;
  }
  if (ok(vec.size() - 2) == false) {
    cout << vec.back();
    return 0;
  }
  int l = -1, r = vec.size() - 1;
  while (r - l > 1) {
    if (ok((l + r) >> 1))
      r = lim;
    else
      l = lim;
  }
  cout << vec[r];
  return 0;
}
