%{
#include <stdio.h>
%}
%%
0[xX][0-9a-fA-F]+    { printf("%s is a hexadecimal number\n", yytext); }
0[0-7]+              { printf("%s is an octal number\n", yytext); }
[1-9][0-9]*          { printf("%s is a decimal number\n", yytext); }
0                    { printf("0 is considered as zero\n"); }
.                    { printf("Invalid input: %s\n", yytext); }
%%

int main() {
    yylex();
    return 0;
}