#include<stdio.h>
#define _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_DEPRECATE
#pragma warning(disable:4996)
int box[10000];
int main()
{
	float a;
	int a1;
	int sum;
	int n;
	int t;
	scanf("%d", &n);
	sum = 0;
	
	while (n--)
	{
		scanf("%f %d", &a, &t);
		a1 = (int)a;

		for (int i = 1; i <= t; i++)
		{
			sum = a1 * i;
			if (box[sum] == 0)
				box[sum] = 1;
			else
				box[sum] = 0;
		}

	}

	for (int i=1; i <= t; i++)
	{
		if (box[i] == 1)
		{
			printf("%d", i);
			return 0;
		}
	}

	return 0;
}