#include"iostream"
const int N = 100010;
int an[N];
int n;
double a;
int t;
using namespace std;
int main()
{
	cin >> n;
	if (n == 0)
	{
		cout << 1;
		return 0;
	}
	while (n--)
	{
		cin >> a >> t;
		for (int i = 1; i <= t; i++)
		{
			double x;
			x = a * i;
			an[(int)x]++;
		}
	}
	int i = 1;
	while (an[i]%2== 0)
	{
		i++;
	}
	cout << i;
	return 0;
}