#include<iostream>
using namespace std;

int main(){
    int n,i,j,t,tem;
    bool l[2000001];
    float a;
    cin>>n;
    for(i=1;i<=2000001;i++){
        l[i]=0;
    }
    for(i=1;i<=n;i++){
        cin>>a>>t;
        for(j=1;j<=t;j++){
            tem=j*a;
            l[tem]=!l[tem];
        }
    }
    for(i=1;i<=2000001;i++){
        if(l[i]==1){ cout<<i<<endl;
        return 0;
        }
    }
    cout<<"error"<<endl;
    return 0;
}