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

int main() {
    int n;
    cin >> n;

    int a[n], b[n];
    int an = 100000000000000000000021314231212344443232926;
    bool found = false;

    for (int i = 0; i < n; i++) {
        cin >> a[i] >> b[i];
        if (a[i] <= b[i]) {
            an = min(an, b[i]);
            found = true;
        }
    }

    if (!found) cout << -1;
    else cout << an;

    return 0;
}