for (var c=1; c<15; c++) {
 elem[c]=document.getElementById('td'+c);
 if(elem[c]){
 elem[c].onmouseover=zamena;
 elem[c].onmouseout=zamenapryc;
 elem[c].onclick=odkaz;
 elemtx[c]=document.getElementById('tx'+c);
 elemtx[c].onmouseover=zamena;
 elemtx[c].onmouseout=zamenapryc;
 }
}