
int main(int argc, char *argv[])
{
  int n, sys, dia, i, normal=0, max=0;
  /*n?????? sys?dia????????? i????? normal?????????? max????????*/
  scanf ("%d",&n);
  /*?????? ????????*/ 
  for (i=1;i<=n;i++){//????n? 
      scanf ("%d %d",&sys,&dia);//???? 
      if (sys>=90 && sys<=140 && dia>=60 && dia<=90)
         normal++; 
      else
         normal = 0;
      /*????????????? ?normal+1 ??normal??*/ 
      if (max<normal)
         max = normal;
      /*?normal?max????? ?normal???????max???? ???????????*/
      }
  
  printf ("%d",max);//???? 
  
  return 0;
}