// taken from dietlibc

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

int atoi(const char* s) {
  long int v=0;
  int sign=1;
  while ( *s == ' '  ||  (unsigned int)(*s - 9) < 5u) s++;
  switch (*s) {
  case '-': sign=-1;
  case '+': ++s;
  }
  while ((unsigned int) (*s - '0') < 10u) {
    v=v*10+*s-'0'; ++s;
  }
  return sign==-1?-v:v;
}