#include<stdio.h>
#include<math.h>
int x[2000005],n,i,j,c;
float a,b;
int main()
{
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%f %f",&a,&b);
		for(j=1;j<=b;j++)
		{
			c=floor(j*a);
			if(x[c-1]==0)
			{
				x[c-1]=1;
			}
			else
			{
				x[c-1]=0;
			}
		}
	}
	for(i=0;i<2000005;i++)
	{
		if(x[i]==1)
		{
			printf("%d",i+1);
		}
	}
	return 0;
}

from math import floor
n=int(input())
ls=[0]*10000000
for i in range(n):
    a,b=map(eval,input().split())
    for i in range(1,b+1):
        j=floor(i*a)
        if ls[j-1]==0:
            ls[j-1]=1
        else:
            ls[j-1]=0
for i in ls:
    if i==1:
        print(ls.index(i)+1)
        break