char *myStrStr(const char *s1, const char *s2) {
  if (!*s2) return NULL;
  char *p1 = (char*)s1;
  while (*p1) {
    char *p1Copy = p1;
    char *p2 = (char*)s2;
    while (*p1 && *p2 && *p1 == *p2) {
      p1++;
      p2++;
    }
    if (!*p2){
      return p1Copy;
    }
    p1 = p1Copy + 1;
  }
  return NULL;
}