#include <bits/stdc++.h>
#define int unsigned long long
using namespace std;
int n,a[15],b[15],ans,cnt=2,mul;
signed main()
{
    cin>>n;
    for(int i=1;i<=n;i++) cin>>a[i]>>b[i];
    ans=b[1];
    mul=a[1];
    while(cnt<=n)
    {
        while(ans%a[cnt]==b[cnt])
        {
            mul*=a[cnt];
            cnt++;
        }
        ans+=mul;
    }
    cout<<ans;
    return 0;
}