#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=1e5+5;
int n;
ll a[N],b[N];
ll exgcd(ll a,ll b,ll &x,ll &y)
{
    if (b==0){x=1;y=0;return a;}
    ll d=exgcd(b,a%b,y,x);
    y-=a/b*x;
    return d;
}
ll inverse(ll v,ll m)
{
    ll res,k;
    exgcd(v, m, res, k);
    return (res%m+m)%m;
}
int main()
{
    cin>>n;
    for (int i=1;i<=n;i++)
        cin>>a[i]>>b[i];
    ll t0=b[1], t1=a[1];
    for (int i=2;i<=n;i++)
    {
        ll g=__gcd(a[i],t1);
        ll d=b[i]-t0;
        d/=g;
        ll in=inverse(t1/g,a[i]/g);
        d=(d*in)%(a[i]/g);
        if (d<0) d+=a[i]/g;
        t0+=d*t1;
        t1=t1/g*a[i];
        t0=(t0%t1+t1)%t1;
    }
    t0 = (t0 % t1 + t1) % t1;
    cout<<t0;
    return 0;
}