#include <bits/stdc++.h>

 using namespace std;

 const int MAXN = ;

 int a[MAXN], b[MAXN];

 set<int> factor(int x)

 {

     set<int> res;

     for (int i = ; i * i <= x; i++)

     {

         if (x % i == )

         {

             res.insert(i);

             while (x % i == ) x /= i;

         }

     }

     if (x != ) res.insert(x);

     return res;

 }

 int main()

 {

     int n;

     while (scanf("%d", &n) != EOF)

     {

         for (int i = ; i < n; i++) scanf("%d %d", &a[i], &b[i]);

         set<int>s1 = factor(a[]);

         set<int>s2 = factor(b[]);

         set<int> st;

         for (auto it: s1) st.insert(it);

         for (auto it: s2) st.insert(it);

         for (int i = ; i < n; i++)

         {

             set<int> tmp;

             for (auto it: st)

             {

                 if (it > a[i] && it > b[i]) continue;

                 else if (a[i] % it && b[i] % it) continue;

                 tmp.insert(it);

             }

             st = tmp;

         }

         if (st.empty()) puts("-1");

         else printf("%d\n", *st.begin());

     }

     return ;

 }