#include<bits/stdc++.h>
using namespace std;
long long diophantine(long long a1,long long b1,long long a2,long long b2)
{
    long long a,b,c,d,m,n,xm,ym,xn,yn,q,r,xr,yr,p,tam;
    c=b2-b1;
    a=a1;
    b=a2;
    d=__gcd(a,b);
    m=a;
    n=b;
    xm=1; ym=0;
    xn=0; yn=1;
    while(n!=0) {
        q=m/n;
        r=m%n;
        xr=xm-q*xn;
        yr=ym-q*yn;
        m=n; xm=xn; ym=yn;
        n=r; xn=xr; yn=yr;
    }
    xm*=c/d;
    ym*=c/d;
    p=b/d;
    q=a/d;
    if(xm<0) {
       tam=(abs(xm)/p)+1;
       xm+=p*tam;
       ym-=q*tam;
    }
    return xm;
}
deque<long long> s;
int main() {
    long long i,t,t1,t2,tam,a1,b1,a2,b2,tam2;
    cin >> t;
    for(i=1;i<=t;i++) {
        cin >> t1 >> t2;
        if(t1<0) {
            tam=t2-abs(t1)%t2;
        }
        else
        tam=t1%t2;
        s.push_back(tam);
        s.push_back(t2);
    }
    if(t==1) {cout << 1; return 0;}
    if(t==1) {
        a1=s.back(); s.pop_back();
        a2=s.back(); s.pop_back();
        if(a1<0) {
            cout << t2-abs(tam)%t2;
        }
    }
    while(!s.empty()) {
        a1=s.back(); s.pop_back();
        b1=s.back(); s.pop_back();
        a2=s.back(); s.pop_back();
        b2=s.back(); s.pop_back();
        tam=diophantine(a1,b1,a2,b2)%a2;
        tam2=a1*a2;
        tam=a1%tam2*tam%tam2+b1;
        if(s.empty()) break;
        s.push_back(tam%tam2);
        s.push_back(tam2);
        //cout << tam << tam2;
    }
    cout << tam%tam2;
}