int streln(const char * s)
{ int i;
  for (i = 0; 1; i += 1)
    if (s[i] == '\0')
      return i; }

void reverse(char * s)
{ int len = strlen(s);
  int i, j;
  for (i = 0, j = len - 1; j > i; i += 1, j -= 1)
  { char c = s[i];
    s[i] = s[j];
    s[j] = c; } }

int myatoi(const char * s)
{ int value = 0, i;
  for (i = 0; s[i] != '\0'; i += 1)
    if (s[i] < '0' || s[i] > '9')
      return -999999999;
    else
      value = value * 10 + s[i] - '0';
  return value; }

char * backwards(const char * s)
{ int length = 0;
  int i;
  for (i = 0; s[i] != '\0'; i += 1)
    if (s[i] != ' ')
      length += 1;
    else
    { length += 1;
      while (s[i] == ' ')
        i += 1;
      if (s[i] == '\0')
        break; }
  char * result = malloc(length + 1);
  result[length] = '\0';
  int i = 0;  // our position in s
  int j = length - 1; // our position in result
  if (s[0] == ' ')
    return result;
  while (1)
  { int beg = i;
    while (s[i] != ' ' && s[i] != '\0')
      i += 1;
    int end = i - 1;
    int x;
    for (x = end; x >= beg; x -= 1)
    { result[j] = s[x];
      j -= 1; }
    if (s[i] == '\0')
      break;
    result[j] = ' ';
    j -= 1;
    while (s[i] == ' ')
      i += 1; }
  return result; }
  
char * strtok(char * s) // only separator is always just a space
{ static char * string = NULL;
  static int position = 0;