Language: C++

 <iostream>
#include <stdio.h>
#include <algorithm>
//#include <string>
#include <math.h>
//#include <vector>

using namespace std;


int main() {
  long long int N;
  int a[17];
  int i,keta=0;
  int ans;
  
  cin >> N; 

  while(N>0){
    a[keta] = N%10;
    N /= 10;
    keta++; 
  }

  i=keta-1;
  while(a[i]==9){
    i--;
  }

  if(i==-1){
    ans = 9*keta;
  }else if(i!=0 && a[i]!=0)
    ans = (a[i]-1)+9*(keta-1);
  else if(keta==1)
    ans = a[0];
  else
    ans = 8+9*(keta-1);

  cout << ans;
  
  return 0;
}


Compiler output:
a.cc:1:2: error: expected unqualified-id before '<' token
    1 |  <iostream>
      |  ^
In file included from /usr/include/c++/14/cstdlib:79,
                 from /usr/include/c++/14/bits/stl_algo.h:71,
                 from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/stdlib.h:98:8: error: 'size_t' does not name a type
   98 | extern size_t __ctype_get_mb_cur_max (void) __THROW __wur;
      |        ^~~~~~
/usr/include/stdlib.h:42:1: note: 'size_t' is defined in header '<cstddef>'; this is probably fixable by adding '#include <cstddef>'
   41 | # include <bits/waitstatus.h>
  +++ |+#include <cstddef>
   42 | 
/usr/include/stdlib.h:278:36: error: 'size_t' has not been declared
  278 | extern int strfromd (char *__dest, size_t __size, const char *__format,
      |                                    ^~~~~~
/usr/include/stdlib.h:282:36: error: 'size_t' has not been declared
  282 | extern int strfromf (char *__dest, size_t __size, const char *__format,
      |                                    ^~~~~~
/usr/include/stdlib.h:286:36: error: 'size_t' has not been declared
  286 | extern int strfroml (char *__dest, size_t __size, const char *__format,
      |                                    ^~~~~~
/usr/include/stdlib.h:298:38: error: 'size_t' has not been declared
  298 | extern int strfromf32 (char *__dest, size_t __size, const char * __format,
      |                                      ^~~~~~
/usr/include/stdlib.h:304:38: error: 'size_t' has not been declared
  304 | extern int strfromf64 (char *__dest, size_t __size, const char * __format,
      |                                      ^~~~~~
/usr/include/stdlib.h:310:39: error: 'size_t' has not been declared
  310 | extern int strfromf128 (char *__dest, size_t __size, const char * __format,
      |                                       ^~~~~~
/usr/include/stdlib.h:316:39: error: 'size_t' has not been declared
  316 | extern int strfromf32x (char *__dest, size_t __size, const char * __format,
      |                                       ^~~~~~
/usr/include/stdlib.h:322:39: error: 'size_t' has not been declared
  322 | extern int strfromf64x (char *__dest, size_t __size, const char * __format,
      |                                       ^~~~~~
In file included from /usr/include/stdlib.h:514:
/usr/include/x86_64-linux-gnu/sys/types.h:33:9: error: '__u_char' does not name a type
   33 | typedef __u_char u_char;
      |         ^~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:34:9: error: '__u_short' does not name a type
   34 | typedef __u_short u_short;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:35:9: error: '__u_int' does not name a type
   35 | typedef __u_int u_int;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:36:9: error: '__u_long' does not name a type
   36 | typedef __u_long u_long;
      |         ^~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:37:9: error: '__quad_t' does not name a type
   37 | typedef __quad_t quad_t;
      |         ^~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:38:9: error: '__u_quad_t' does not name a type
   38 | typedef __u_quad_t u_quad_t;
      |         ^~~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:39:9: error: '__fsid_t' does not name a type
   39 | typedef __fsid_t fsid_t;
      |         ^~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:42:9: error: '__loff_t' does not name a type; did you mean '__locale_t'?
   42 | typedef __loff_t loff_t;
      |         ^~~~~~~~
      |         __locale_t
/usr/include/x86_64-linux-gnu/sys/types.h:47:9: error: '__ino_t' does not name a type
   47 | typedef __ino_t ino_t;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:54:9: error: '__ino64_t' does not name a type
   54 | typedef __ino64_t ino64_t;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:59:9: error: '__dev_t' does not name a type
   59 | typedef __dev_t dev_t;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:64:9: error: '__gid_t' does not name a type
   64 | typedef __gid_t gid_t;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:69:9: error: '__mode_t' does not name a type; did you mean '__locale_t'?
   69 | typedef __mode_t mode_t;
      |         ^~~~~~~~
      |         __locale_t
/usr/include/x86_64-linux-gnu/sys/types.h:74:9: error: '__nlink_t' does not name a type
   74 | typedef __nlink_t nlink_t;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:79:9: error: '__uid_t' does not name a type
   79 | typedef __uid_t uid_t;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:97:9: error: '__pid_t' does not name a type
   97 | typedef __pid_t pid_t;
      |         ^~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:103:9: error: '__id_t' does not name a type
  103 | typedef __id_t id_t;
      |         ^~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:114:9: error: '__daddr_t' does not name a type
  114 | typedef __daddr_t daddr_t;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:115:9: error: '__caddr_t' does not name a type
  115 | typedef __caddr_t caddr_t;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:121:9: error: '__key_t' does not name a type
  121 | typedef __key_t key_t;
      |         ^~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:126:
/usr/include/x86_64-linux-gnu/bits/types/clock_t.h:7:9: error: '__clock_t' does not name a type
    7 | typedef __clock_t clock_t;
      |         ^~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:128:
/usr/include/x86_64-linux-gnu/bits/types/clockid_t.h:7:9: error: '__clockid_t' does not name a type
    7 | typedef __clockid_t clockid_t;
      |         ^~~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:129:
/usr/include/x86_64-linux-gnu/bits/types/time_t.h:10:9: error: '__time_t' does not name a type
   10 | typedef __time_t time_t;
      |         ^~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:130:
/usr/include/x86_64-linux-gnu/bits/types/timer_t.h:7:9: error: '__timer_t' does not name a type
    7 | typedef __timer_t timer_t;
      |         ^~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:134:9: error: '__useconds_t' does not name a type
  134 | typedef __useconds_t useconds_t;
      |         ^~~~~~~~~~~~
/usr/include/x86_64-linux-gnu/sys/types.h:138:9: error: '__suseconds_t' does not name a type
  138 | typedef __suseconds_t suseconds_t;
      |         ^~~~~~~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/sys/types.h:155:
/usr/include/x86_64-linux-gnu/bits/stdint-intn.h:24:9: error: '__int8_t' does not name a type; did you mean '__int128_t'?
   24 | typedef __int8_t int8_t;
      |         ^~~~~~~~
      |         __int128_t
/usr/include/x86_64-linux-gnu/bits/stdint-intn.h:25:9: error: '__int16_t' does not name a type; did you mean '__int128_t'?
   25 | typedef __int16_t int16_t;
      |         ^~~~~~~~~
      |         __int128_t
/usr/include/x86_64-linux-gnu/bits/stdint-intn.h:26:9: error: '__int32_t' does not name a type; did you mean '__int128_t'?
   26 | typedef __int32_t int32_t;
      |         ^~~~~~~~~
      |         __int128_t
/usr/include/x86_64-linux-gnu/bits/stdint-intn.h:27:9: error: '__int64_t' does not name a type; did you mean '__int128_t'?
   27 | typedef __int64_t int64_t;
      |         ^~~~~~~~~
      |         __int128_t
/usr/include/x86_64-linux-gnu/sys/types.h:158:9: error: '__uint8_t' does not name a type; did you mean '__uint128_t'?
  158 | typedef __uint8_t u_int8_t;
      |         ^~~~~~~~~
      |         __uint128_t
/usr/include/x86_64-linux-gnu/sys/types.h:159:9: error: '__uint16_t' does not name a type; did you mean '__uint128_t'?
  159 | typedef __uint16_t u_int16_t;
      |         ^~~~~~~~~~
      |         __uint128_t
/usr/include/x86_64-linux-gnu/sys/types.h:160:9: error: '__uint32_t' does not name a type; did you mean '__uint128_t'?
  160 | typedef __uint32_t u_int32_t;
      |         ^~~~~~~~~~
      |         __uint128_t
/usr/include/x86_64-linux-gnu/sys/types.h:161:9: error: '__uint64_t' does not name a type; did you mean '__uint128_t'?
  161 | typedef __uint64_t u_int64_t;
      |         ^~~~~~~~~~
      |         __uint128_t
In file included from /usr/include/endian.h:35,
                 from /usr/include/x86_64-linux-gnu/sys/types.h:176:
/usr/include/x86_64-linux-gnu/bits/byteswap.h:33:17: error: '__uint16_t' does not name a type; did you mean '__uint128_t'?
   33 | static __inline __uint16_t
      |                 ^~~~~~~~~~
      |                 __uint128_t
/usr/include/x86_64-linux-gnu/bits/byteswap.h:48:17: error: '__uint32_t' does not name a type; did you mean '__uint128_t'?
   48 | static __inline __uint32_t
      |                 ^~~~~~~~~~
      |                 __uint128_t
/usr/include/x86_64-linux-gnu/bits/byteswap.h:69:31: error: '__uint64_t' does not name a type; did you mean '__uint128_t'?
   69 | __extension__ static __inline __uint64_t
      |                               ^~~~~~~~~~
      |                               __uint128_t
In file included from /usr/include/endian.h:36:
/usr/include/x86_64-linux-gnu/bits/uintn-identity.h:32:17: error: '__uint16_t' does not name a type; did you mean '__uint128_t'?
   32 | static __inline __uint16_t
      |                 ^~~~~~~~~~
      |                 __uint128_t
/usr/include/x86_64-linux-gnu/bits/uintn-identity.h:38:17: error: '__uint32_t' does not name a type; did you mean '__uint128_t'?
   38 | static __inline __uint32_t
      |                 ^~~~~~~~~~
      |                 __uint128_t
/usr/include/x86_64-linux-gnu/bits/uintn-identity.h:44:17: error: '__uint64_t' does not name a type; did you mean '__uint128_t'?
   44 | static __inline __uint64_t
      |                 ^~~~~~~~~~
      |                 __uint128_t
In file included from /usr/include/x86_64-linux-gnu/sys/select.h:37,
                 from /usr/include/x86_64-linux-gnu/sys/types.h:179:
/usr/include/x86_64-linux-gnu/bits/types/struct_timeval.h:14:3: error: '__time_t' does not name a type; did you mean '__sigset_t'?
   14 |   __time_t tv_sec;              /* Seconds.  */