#include <bits/stdc++.h>
using namespace std;
//
#define ll long long
#define ull unsigned long long
#define pb push_back
#define mx 100010
#define mod 1000000007
#define inf INT_MAX
#define pi acos(-1)
#define endl '\n'
#define fin freopen("input", "r", stdin)
#define Fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
//

set<ll> se;
vector<ll> v;

void sieve()
{
    bool isprime[mx];
    for (int i = 0; i <= mx; i++)
    {
        isprime[i] = true;
    }
    for (int i = 3; i * i <= mx; i += 2)
    {
        if (isprime[i])
        {
            for (int j = i * i; j <= mx; j += i + i)
            {
                isprime[j] = false;
            }
        }
    }
    v.pb(2);
    for (int i = 3; i <= mx; i += 2)
    {
        if (isprime[i])
        {
            v.pb(i);
        }
    }
}

void prime_divisor(ll x) {
    vector<ll>::iterator it;
    for (it = v.begin(); it != v.end(); it++) {
        if (*it > x) break;
        else if (x % *it == 0) {
            se.insert(*it);
            se.insert(x / *it);
        }
    }
}

int main() {
    sieve();
    ll t, a, b;
    cin >> t;

    scanf("%lld %lld", &a, &b);

    ll x = sqrt(a);
    prime_divisor(x);
    x = sqrt(b);
    prime_divisor(x);

    for (ll i = 1; i < t; i++) {
        scanf("%lld %lld", &a, &b);

        for (auto it1 = se.begin(); it1 != se.end(); it1++) {
            if (a % *it1 == 0 || b % *it1 == 0) {
                break;
            }
            else {
                se.erase(it1);
            }
        }
    }

    if (se.size() >= 1) cout << *se.begin() << endl;
    else cout << -1 << endl;
}