CodeForces - 1025B Weakened Common Divisor

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN=150000+100;
ll a[MAXN],b[MAXN];

int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)
        scanf("%lld %lld",&a[i],&b[i]);
    ll gcd=a[0]*b[0]/__gcd(a[0],b[0]);
    for(int i=1;i<n;i++)
        gcd=__gcd(gcd,a[i]*b[i]/__gcd(a[i],b[i]));
    if(gcd==1)
    {
        printf("-1\n");
        return 0;
    }
    ll temp;
    for(int i=0;i<n;i++)
    {
        temp=__gcd(gcd,a[i]);
        if(temp>1){
            gcd=temp;
            continue;
        }
        temp=__gcd(gcd,b[i]);
        if(temp>1)
            gcd=temp;
    }
    printf("%lld\n",gcd);
    return 0;
}