int n,high,low,s,ans;//n?????high,low????????????????,s??????????????ans???
int main()
{
  cin>>n;//??
  for(;n--;)//??n?
  {
    cin>>high>>low;//????????????????
    if(90<=high&&high<=140&&60<=low&&low<=90)//??
    {
      ++s;//?????????
      if(s>ans)//????
        ans=s;
    }
    else//???
      s=0;//?????????
  }
  cout<<ans<<endl;//??
  return 0;
}
