#include<iostream>
#include<cstdio>
#define ll long long
using namespace std;
const int N=20;
ll n,a[N],b[N],mx,t=1,k;
char ch;
inline void read(ll &x){x=0;ch=getchar();while(ch<48||ch>57)ch=getchar();while(ch>47&&ch<58)x=(x<<3)+(x<<1)+(ch^48),ch=getchar();}
bool check(ll x)
{
    for(int i=1;i<=n;++i)
        if(x%a[i]!=b[i]) return 0;
    return 1;
}
int main()
{
    freopen("ccyz.in","r",stdin);
    freopen("ccyz.out","w",stdout);
    read(n);
    for(int i=1;i<=n;++i)
    {
        read(a[i]),read(b[i]),t*=a[i];
        if(a[i]>mx)
        {
            mx=a[i];
            k=b[i];
         } 
    }
    for(ll i=1;mx*i<=t;++i)
        if(check(mx*i+k))
        {
            printf("%lld\n",mx*i+k);
            break;
        }
    return 0;
}