#include<map>
#include<list>
#include<stack>
#include<queue>
#include<cmath>
#include<queue>
#include<stack>
#include<deque>
#include<math.h>
#include<cstdio>
#include<string>
#include<vector>
#include<cstring>
#include<fstream>
#include<stdio.h>
#include<sstream>
#include<iomanip>
#include<iostream>
#include<string.h>
#include<algorithm>
#include<bits/stdc++.h>
using namespace std;
#define LL long long
const int N=1e6+10;
const int INF=0x3f3f3f3f;
long long n,a,b,x,y,z;
int main()
{
	cin>>n>>x>>y;
	z=y;
	for(long long i=2;i<=n;i++)
	{
		cin>>a>>b;
		z=y;
		while(z%a!=b)
		{
			z+=x;
		}
		x*=a;
		y=z%x;
	}
	cout<<z;
	return 0;
}