#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;
int n,spice[20][3],ans=0x3f3f3f3f;
void search(int sour,int bitter,int cnt){
	if(cnt > n){
		ans = (sour == 1&&bitter == 0)?ans:min(ans,abs(sour-bitter));
		return;
	}
	search(sour*spice[cnt][0],bitter+spice[cnt][1],cnt++);
	search(sour,bitter,cnt++);
}
int main(){
	scanf("%d",&n);
	for(int i = 1;i <= n;i++) scanf("%d%d",&spice[i][0],&spice[i][1]);
	search(1,0,1);
	printf("%d",ans);
	return 0;
}