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

#define int long long
#define ll long long

int modmul(int a, int b, int M) {
	long long ret = a * b - M * (int)(1.L / M * a * b);
	return ret + M * (ret < 0) - M * (ret >= (ll)M);
}
int modpow(int b, int e, int mod) {
	int ans = 1;
	for (; e; b = modmul(b, b, mod), e /= 2)
		if (e & 1) ans = modmul(ans, b, mod);
	return ans;
}
bool prime(int n) {
	if (n < 2 || n % 6 % 4 != 1) return (n | 1) == 3;
	int A[] = {2, 325, 9375, 28178, 450775, 9780504, 1795265022},
	    s = __builtin_ctzll(n-1), d = n >> s;
	for (int a : A) {   // ^ count trailing zeroes
		int p = modpow(a%n, d, n), i = s;
		while (p != 1 && p != n - 1 && a % n && i--)
			p = modmul(p, p, n);
		if (p != n-1 && i != s) return 0;
	}
	return 1;
}
int pollard(int n) {
	auto f = [n](int x) { return modmul(x, x, n) + 1; };
	int x = 0, y = 0, t = 30, prd = 2, i = 1, q;
	while (t++ % 40 || __gcd(prd, n) == 1) {
		if (x == y) x = ++i, y = f(x);
		if ((q = modmul(prd, max(x,y) - min(x,y), n))) prd = q;
		x = f(x), y = f(f(y));
	}
	return __gcd(prd, n);
}
vector<int> factor(int n) {
	if (n == 1) return {};
	if (prime(n)) return {n};
	int x = pollard(n);
	auto l = factor(x), r = factor(n / x);
	l.insert(l.end(), begin(r), end(r));
	return l;
}
struct custom_hash { // Credits: https://codeforces.net/blog/entry/62393
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}
	size_t operator()(uint64_t a) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(a + FIXED_RANDOM);
	}
	template<class T> size_t operator()(T a) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		hash<T> x;
		return splitmix64(x(a) + FIXED_RANDOM);
	}
	template<class T, class H> size_t operator()(pair<T, H> a) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		hash<T> x;
		hash<H> y;
		return splitmix64(x(a.f) * 37 + y(a.s) + FIXED_RANDOM);
	}
};
template<class T, class H> using umap = unordered_map<T, H, custom_hash>;
template<class T> using uset = unordered_set<T, custom_hash>;

 
int n;
vector<pair<int, int>> a;
vector<set<int>> hld;
umap<int, int> cnt;
 
int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	cin >> n;
	a.resize(n);
	for(auto& i: a) {
		cin >> i.first >> i.second;
	}
	for(int i = 0; i < n; ++i) {
		vector<int> hld1, hld2;
		hld1 = factor(a[i].first);
		hld2 = factor(a[i].second);
		set<int> se;
		for(auto& j: hld1) {
			se.insert(j);
		}
		for(auto& j: hld2) {
			se.insert(j);
		}
		hld.emplace_back(se);
	}
	for(auto& i: hld) {
		for(auto& j: i) {
			++cnt[j];
		}
	}
	for(auto& i: cnt) {
		if(i.second == n) {
			cout << i.first << "\n";
			return 0;
		}
	}
	cout << -1 << "\n";
}