02a.l

   1 %option noyywrap
   2 %option noinput
   3 %option nounput
   4 %{
   5 #include <stdio.h>
   6 int x = 0, z = 0;
   7 %}
   8
   9 %%
  10 forward\ [0-9] x += atoi(yytext+sizeof("forward"));
  11 up\ [0-9]      z -= atoi(yytext+sizeof("up"));
  12 down\ [0-9]    z += atoi(yytext+sizeof("down"));
  13 \n      ;
  14 %%
  15
  16 int main (void)
  17 {
  18         yylex();
  19         printf("%d\n", x*z);
  20         return 0;
  21 }