//***************************
//**???6.cpp
//**??????
//**???2013.10.23
//**?????????
//***************************
//??????????????????????????????
int main()
{
	// n????????a?????????????b?????????????j?k???
	int n, high, low, a[100], b[50], j = 0, k = 0, max = 0;
	cin >> n;

	for (int i = 1; i <= n; i++)
	{
		cin >> high >> low;

		a[i] = (high <= 140 && high >= 90 && low <= 90 && low >= 60);
		if (a[i] == 0) // ??????
		{
			j++; // b????????
			k = 0; // ??????0
		}
		else // ?????
		{
			k++; // ?????1
			b[j] = k;
			if (b[j] > max)
				max = b[j];
		}
	}
	cout << max << endl;
	return 0;
}