#include <msvcrt/ctype.h>
#include <msvcrt/stdlib.h>

__int64
_wtoi64(const wchar_t *nptr)
{
  wchar_t *s = (wchar_t *)nptr;
  __int64 acc = 0;
  int neg = 0;

  while(iswspace((int)*s))
    s++;
  if (*s == '-')
    {
      neg = 1;
      s++;
    }
  else if (*s == '+')
    s++;

  while (iswdigit((int)*s))
    {
      acc = 10 * acc + ((int)*s - '0');
      s++;
    }

  if (neg)
    acc *= -1;
  return acc;
}