#include 
#include 

%%{
  machine test;

  action one { printf("%c\n", *(&fc-1)); }
  action two { printf("%c%c\n", *(&fc-2), *(&fc-1)); }
  action ans { exit(0); }

  TheUnknown = (
    start: (
      [4] -> StartsWithFour |
      (digit - [4]) -> OneDigit
    ),
    StartsWithFour: (
      [2] @ans -> final |
      (digit - [2]) -> TwoDigits |
      '\n' @one -> start
    ),
    OneDigit: (
      digit -> TwoDigits |
      '\n' @one -> start
    ),
    TwoDigits: (
      '\n' @two -> start
    )
  );

  #ans = '42\n' @{ fbreak; exit(0); };
  #one = digit '\n' @{ printf("%s\n", (p - 2)); };
  #two = digit digit '\n' @{ printf("%s%s\n", (p - 2), (p - 1)); };

  #main := (ans | one | two)*;
  main := TheUnknown;
}%%

#define BUFSIZE 100

%% write data;

int main()
{
  char buf[BUFSIZE];
  char *p;
  int cs;
  while (fgets(buf, sizeof(buf), stdin) != 0) {
    p = buf;
    %%{
      write init;
      write exec noend;
    }%%
  }
  return 0;
}