#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
int n, m;
pii arr[2000010];
int brr[2000010];
vector<int> G[2000010];
bool vis[2000010];
int cnt_point, cnt_edge, Max, MMax;
int Get(int x) { return lower_bound(brr + 1, brr + 1 + m, x) - brr; }
void DFS(int u) {
  if (brr[u] > Max) {
    MMax = Max;
    Max = brr[u];
  } else if (brr[u] > MMax)
    MMax = brr[u];
  ++cnt_point;
  cnt_edge += G[u].size();
  vis[u] = 1;
  for (auto v : G[u])
    if (!vis[v]) DFS(v);
}
void Run() {
  while (scanf("%d", &n) != EOF) {
    m = 0;
    for (int i = 1; i <= n; ++i) {
      scanf("%d%d", &arr[i].first, &arr[i].second);
      brr[++m] = arr[i].first;
      brr[++m] = arr[i].second;
    }
    sort(brr + 1, brr + 1 + m);
    m = unique(brr + 1, brr + 1 + m) - brr - 1;
    for (int i = 1; i <= m; ++i) G[i].clear();
    memset(vis, 0, sizeof vis);
    for (int i = 1; i <= n; ++i) {
      arr[i].first = Get(arr[i].first);
      arr[i].second = Get(arr[i].second);
      int u = arr[i].first, v = arr[i].second;
      G[u].push_back(v);
      G[v].push_back(u);
    }
    int res = 0;
    for (int i = 1; i <= m && res != -1; ++i)
      if (!vis[i]) {
        cnt_point = cnt_edge = 0;
        Max = MMax = 0;
        DFS(i);
        cnt_edge >>= 1;
        if (cnt_point > cnt_edge)
          res = max(res, MMax);
        else if (cnt_point == cnt_edge)
          res = max(res, Max);
        else
          res = -1;
      }
    printf("%d\n", res);
  }
}
int main() {
  Run();
  return 0;
}
