function autoTab(input,len, e) {
  if(input.value.length >= len) {
    input.value = input.value.slice(0, len);
    input.form[(getIndex(input)+1) % input.form.length].focus();
  }

  function getIndex(input) {
    var index = -1, i = 0, found = false;
    while (i < input.form.length && index == -1)
    if (input.form[i] == input)index = i;
    else i++;
    return index;
  }
  return true;
}