#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll exgcd(ll a,ll b ,ll &x, ll &y)
{
	if(!b){
		x=1,y=0;
		return a;
	}
	ll d=exgcd(b,a%b,y,x);
	y-=a/b*x;
	return d;
}
int main()
{
	int n;
	ll a1,b1,a2,b2;
	cin>>n;
	cin>>a1>>b1;
	for(int i=0;i<n-1;i++){
		cin>>a2>>b2;
		ll x,y,d;
		d=exgcd(a1,a2,x,y);
		x*=(b2-b1)/d;
		ll t=a2/d;
		x=(x%t+t)%t;
		b1=x*a1+b1;
		a1=abs(a1/d*a2);
	}
	cout<<(b1%a1+a1)%a1;
	return 0;
}