#include<iostream>
#include<cmath>
using namespace std;
int n,b[1000],a,t,c[1000];
int main()
{
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> a >> t;
		c[i] = floor(a * t);
	}
	for (int j = 1; j <= c[j]; j++)//c数组的值为偶数时表示灯关为奇数时表示灯开
	{
		b[j] += 1;
	}
	for (int k = 1; k <= 1000; k++)
	{
		if (b[k] % 2 != 0)
		{
			cout << k;
			break;
		}
	}
	return 0;
}