function MaxTextboxChars(pocet, t)
{ 
  if(t.value.length >= pocet - 1) t.value = t.value.substr(0, pocet - 1);
}

function MaxTextboxCharsWithDisplay(pocet, t, idCharsWritten, idCharsLeft)
{ 
  if(t.value.length >= pocet - 1) t.value = t.value.substr(0, pocet - 1);  
  idCharsWritten.innerHTML = t.value.length;
  idCharsLeft.innerHTML = pocet - t.value.length;
}