#include<iostream>
using namespace std;
int light[2000050] = { 0 };
int main()
{
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		double a;
		int t;
		cin >> a >> t;
		for (int j = 1; j <= t; j++)
		{
			double k = a * t;
			int num = (int)k;
			if (light[num] == 0)
				light[num] = 1;
			else if (light[num] == 1)
				light[num] = 0;
		}
	}
	int i = 1;
	while (light[i] == 0)
		i++;
	cout << i;
	return 0;
}