//***********************************************************
//* ? ??5.cpp                                            *
//* ? ??? ? 1200012916                                 *
//* ? ??2012?10?12?                                   *
//* ? ??????????????????                 *
//***********************************************************

int main() 
{                                //?????
	int c1 = 0, c2 = 0, t = 1;   //??????????????  
	
	//??????????????a?b?
	//????????????c,??????i?n
	int a, b, c, i, n;          
    cin >> n;                    //??n
	for (i = 1; i <= n; i++)
	{
		cin >> a >> b;
		
		//?????????1?0??????
		if (a >= 90 && a <= 140 && b >= 60 && b <= 90)
			c = 1;
		else
			c = 0;
		
		//?if?????????????1?
		//????????????????c1?
		if (t == 1)          
		{
			if (c == 1)
			{
				c1 = c1 + 1;
				t = 1;
			}
			else
				t = 0;
		}
	    
		//??????0??c1?c2???
		//??????c2,??c1?0
		else                          
		{
			if (c1 > c2)
				c2 = c1;
			c1 = 0;
			if (c == 1)
			{ 
				c1 = c1 + 1;
				t = 1;
			}
			else
				t = 0;
		}
		
		//??c1?c2??????????c2
		if(c1 > c2)
			c2 = c1;
	}
	cout << c2 <<endl;           //??c2
	
	return 0;
}                                //?????

     
