function sumin(mode, rate, fee, max){
 if (mode == 0) {
// from first sum
   ins = document.forms['main'].is.value;
   com = ins * fee;
   out = ins * rate;
 };
 if (mode == 1) {
// from sum with fee
   com = document.forms['main'].isc.value;
   ins = com / fee;
   out = ins * rate;
 };
 if (mode == 2) {
// from result sum
   out = document.forms['main'].os.value;
   ins = out / rate;
   com = ins * fee;
 };
// check if fee is too low
 checkfee = com - ins;
 if (checkfee < 0.01) {
   com = parseFloat(ins) + 0.01;
 };
// check if fee is too high
 if (max != 0) {
   if (checkfee > max) {
     com = parseFloat(ins) + max;
   };
 };
// prepare data to show
 ins = Math.ceil(ins*100);
 document.forms['main'].is.value = ins / 100;
 com = Math.ceil(com*100);
 document.forms['main'].isc.value = com / 100;
 out = Math.floor(out*100);
 document.forms['main'].os.value = out / 100;

}

function suminplain(mode, rate, fee, max){
 if (mode == 0) {
// from first sum
   ins = document.forms['main'].is.value;
   out = ins * rate;
 };
 if (mode == 2) {
// from result sum
   out = document.forms['main'].os.value;
   ins = out / rate;
 };
// prepare data to show
 ins = Math.ceil(ins*100);
 document.forms['main'].is.value = ins / 100;
 out = Math.floor(out*100);
 document.forms['main'].os.value = out / 100;

}

function noedit () {
 document.forms['main'].is.focus();
}