#include<iostream>
#include<stdio.h>
#include<math.h>
int deng[2000001] = { 0 };
using namespace std;
int main()
{
	int n, t, i, j, chang;
	
	double a;
	scanf("%d", &n);
	for (j = 0; j < n; j++)
	{
		scanf("%f %d", &a, &t);
		for (i = 1; i <= t; i++)
		{
			chang = (int)(a * i);
			deng[chang] = deng[chang]+1;
		}
	}
	for (j = 0;; j++)
	{
		if (deng[j]%2== 1)
			printf("%d", j);
		if (deng[j]%2== 1)
			break;
	}
	return 0;
}