#include<iostream>

#include<cstdio>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<stack>

#include<queue>

#include<deque>

#include<set>

#include<vector>

#include<map>

#include<functional>

#define fst first

#define sc second

#define pb push_back

#define mem(a,b) memset(a,b,sizeof(a))

#define lson l,mid,root<<1

#define rson mid+1,r,root<<1|1

#define lc root<<1

#define rc root<<1|1

#define lowbit(x) ((x)&(-x)) 

using namespace std;

typedef double db;

typedef long double ldb;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> PI;

typedef pair<ll,ll> PLL;

const db eps = 1e-;

const int mod = 1e9+;

const int maxn = 2e7+;

const int maxm = 2e6+;

const int inf = 0x3f3f3f3f;

const db pi = acos(-1.0);

inline int read(){

    int num;

    char ch;

    while((ch=getchar())<'' || ch>'');

    num=ch-'';

    while((ch=getchar())>='' && ch<=''){

        num=num*+ch-'';

    }

    return num;

}

int c = ;

int p[maxn];

void d(int x){

    for(int i=;1ll*i*i<=x;i++)if(x%i==){

        p[c++]=i;

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

    }

    if(x>)p[c++]=x;

}

ll gcd(ll a, ll b){

    return b ==  ? a : gcd(b, a % b);

}

PLL pa[ + ];

bool cmp(PLL a, PLL b){

    return max(a.fst, a.sc) < max(b.fst, b.sc);

}

int main() {

    int n;

    scanf("%d", &n);

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

        scanf("%I64d %I64d", &pa[i].fst, &pa[i].sc);

    }

    //sort(pa, pa+n, cmp);

    d(pa[].fst);

    d(pa[].sc);

    if(n==){

        printf("%I64d", pa[].fst);

        return ;

    }

    for(int i = ; i < c; i++){

        int flg = ;

        for(int j = ; j < n && flg; j++){

            if(pa[j].fst%p[i]!= && pa[j].sc%p[i]!=) flg = ;

        }

        if(flg){

            printf("%d", p[i]);

            return ;

        }

    }

    printf("-1");

    return ;

}