/**

 *中国剩余定理

 */

#include<iostream>

#include<cstdio>

#include<map>

#include<cstring>

#include<string>

#include<algorithm>

#include<queue>

#include<vector>

#include<stack>

#include<cstdlib>

#include<cctype>

#include<cstring>

#include<cmath>

#define  LL __int64

using namespace std;

/**

 *gcd(a,b)=d;则存在x,y,使d=ax+by

 *extended_euclid(a,b)=ax+by

 */

LL extended_euclid(LL a,LL b,LL &x,LL &y){//扩张欧几里的算法

    int d;

    if(b==){

        x=; y=;

        return a;

    }

    d=extended_euclid(b,a%b,y,x);

    y=y-a/b*x;

    return d;

}

/**

 *x=b[i](modw[i]) o<i<len

 *w[i]>0,且w[]中任意两个数互质

 */

LL chinese_remainder(int b[],int w[],int len){

    LL res,i,d,x,y,n,m;

    res=; n=;

    for(i=;i<len;i++) n*=w[i];

    for(i=;i<len;i++){

        m=n/w[i];

        extended_euclid(w[i],m,x,y);

        res=(res+y*m*b[i])%n;

    }

    return (n+res%n)%n;

}

int main()

{

    int len,b[],w[];

    while(cin>>len){

        for(int i=;i<len;i++){

            cin>>w[i]>>b[i];

        }

        cout<<chinese_remainder(b,w,len)<<endl;

    }

    return ;

}