#include <stdio.h>
#include <stdlib.h>
int xtoi(char c)
{
int v = -1;
char w=toupper(c);
if(w >= 'A' && w <= 'F'){
v = w - 'A' + 0x0A;
}else if (w >= '0' && w <= '9'){
v = w - '0';
}
return v;
}
int main(int argc,char **argv)
{
printf("v:%p\n",argc == 2 ? xtoi(argv[1][0]):-1);
return 0;
}