#include<stdio.h>

int main(){
	int n;
	int l[2000001]={0};
	float a[5001]={0};
	int t[5001]={0};
	scanf("%d",&n);
	int i=1;
	while(i<=n){
		scanf("%f %d",&a[i],&t[i]);
		i++;
	}
	int z=1;
	while(z<=n){
		int o=1;
		while(o<=t[z]){
			l[(int)(o*a[z]*1.0)]=!l[(int)(o*a[z]*1.0)];
			o++;
		}
		z++;
	}
	int r=1;
	while(!l[r]){
		r++;
	}
	printf("%d",r);
	return 0;
}