//********************************
//*???????   **
//*?????? 1300012713 **
//*???2013.10.24  **
//********************************
int main() 
{
	int m = 0, p = 0, n, a, b; // ???????m,p,????n????a????b
	cin >> n; //??????n
	for (int i = 1; i <= n; i++) //?????
	{
		cin >> a >> b; //?????a????b
		if(a >= 90 && a <= 140 && b >= 60 && b <=90) //????????
			m = m + 1; //??????
		else //??
		{
			if (p == 0) //??p???????????m
				p = m;
			else if (p > 0 && p < m) //??p??????m???m??
				p = m;
			m = 0; //m??
		}
	}
	if (p < m) //??p?m 
		p = m;
	cout << p << endl; //?????
	return 0;
}

