
//**************************************************************************
//??????
//??????
//???2012.10.10
//**************************************************************************

int main()
{
	int n,i;                                  //????n?????i
	int x,y,hours,max;                        //?????????x??????y??????hours????????max
	cin >> n;
	int a[100],b[100],c[102];                 //??a?b??????????????c????????
	x=1;
	y=0;
	hours=0;
	max=0;
	memset(a,0,sizeof(a));
    memset(b,0,sizeof(b));
	memset(c,0,sizeof(c));                    //?????
    for (i=0;i<n;i++)         
	{
		cin >> a[i] >> b[i];
		//cout << "????????" << endl;
	}
	for (i=0;i<n;i++)
	{
		if ((a[i]<=140)+(a[i]>=90)+(b[i]<=90)+(b[i]>=60)==4)
			c[i+1]=1;
		else c[i+1]=0;                        //??????1?????0???????????????0?1?????
	}
    for (i=1;i<=n;i++)
	{
		if ((c[i-1]==0)+(c[i]==1)==2)
			x=i;
		if ((c[i]==1)+(c[i+1]==0)==2)
			y=i;           
		hours=y-x+1;                          //??c????1????????????
		max=max > hours ? max : hours;        //?????hours???max
	}

    cout << max << endl;

return 0;
}