//****************************
//*???:6.cpp               *
//*??:??                  *
//*????:2013?10?30?     *
//*????:????          *
//****************************
int main()
{
	int n, a, b, t, x, max;  //????n
	cin >> n;
	x = 0;
	max = 0;
	for ( int i = 1; i <= n; i ++ )
	{
		cin >> a >> b;
		t = ( a >= 90 ) && ( a <= 140 ) && ( b >= 60 ) && ( b <= 90 );
		if ( t == 1 )
		{
			x = x + 1;
			if ( x >= max )
				max = x;
		}
		else
		{
			if ( x >= max )
				max = x;
			x = 0;
		}
	}
	cout << max;
	return 0;
}