#include <stdio.h>
int main()
{
	int n;
	double a[5001];
	int ax[5001];
	int t[5001];
	int max=0;
	int N[2000001] = { 0 };
	int number=0;
	scanf("%d", &n);
	for (int i = 1; i <= n; i++)
	{
		scanf("%lf%d", &a[i], &t[i]);
		ax[i] = (int)a[i];
		if (ax[i] * t[i] > max)
		{
			max = ax[i] * t[i];
		}
	}
	for (int x = 1; x <= n; x++)
	{
		for (int y = 1; y <= t[x]; y++)
		{
			if (N[y * ax[x]] == 0)
			{
				N[y * ax[x]] = 1;
			}
			else
			{
				N[y * ax[x]] = 0;
			}
		}
	}
	for (int k = 1; k <= max; k++)
	{
		if (N[k] == 1)
		{
			number = k;
		}
	}
	printf("%d", number);
	return 0;
}