#include<stdio.h>
#include<stdlib.h>

#ifdef HEAD
static int Z = 1;
#elif defined(TAIL)
static int Z = -1;
#else
static int Z = 0;
#endif

static int u, b, e, l = 1;
static char *d = NULL, *p, *q, *r;

static void f(void)
{
   fwrite(d, q - d, 1, stdout);
}

static void t(char *s)
{
   e -= s - d;
   for(p = d; p != d + e;)
      *p++ = *s++;
}

int main(int z, char **v)
{
   if( z - 2 )
   {
      return printf("%s {line_%s}\n", *v, Z ? "count" : "number");
   }

   u = atoi(v[1]);
   u = Z ? abs(u) * Z : u;

   b = e = z = 0;
   while( !z )
   {
      if( e == b )
      {
         if( !(d = (char*)realloc(d, b += 4096)) )
         {
            fprintf(stderr, "Out of memory (need %d)\n", b);
            return 1;
         }
      }
      e += fread(d + e, 1, b - e, stdin);
      z = e < b;

      if( u >= 0 && Z >= 0 )
      {
         for(p = q = d; p != d + e; l += *p++ == '\n')
         {
            if( Z ? l <= u : l != u )
               *q++ = *p;
         }
         f();
         e = 0;
      }
      else if( e && u )
      {
         q = r = d + e;
         q -= q[-1] == '\n';

         for(l = -1; d - q--;)
         {
            if( *q == '\n' )
            {
               l--;
               if( l < u )
               {
                  l++;
                  break;
               }
               r = q + 1;
            }
         }
         q++;

         if( !Z )
         {
            f();
         }

         t(q);

         if( z )
         {
            if( !Z && l == u )
            {
               t(r -= q - d);
            }
            q = d + e;
            f();
         }
      }
   }

   return 0;
}