function Calc(type) {
     
      if(type == 'express'){
        var tf = document.getElementById('express');
        var stavka = 21;
        var ek = 4;
        if (summa == '') {
    	    document.getElementById('express_month_pay').innerHTML = '--';
    	  }
      }
      
      if(type == 'auto'){
        var tf = document.getElementById('auto');
        var stavka = 21;
        var ek = 20;
        if (summa == '') {
    	    document.getElementById('auto_month_pay').innerHTML = '--';
    	  }
      }
      
    	var summa = parseFloat(tf.summa.value);
     	var months = parseFloat(tf.months.value); 

    	
    	var ps = eval(stavka/100/12);
    	
    	var x = eval(1+ps);
        var y = eval(Math.pow( x, months ));
        var z = eval(1-1/y);
    	var ap = eval(summa*ps/z);
    	
    	var kp = eval(summa*ek/100);
    	
    	var plat = eval(ap);

      
	  var plat00 = eval(Math.round(plat/100)*100);
      plat = plat.toFixed(0);
      kp = kp.toFixed(0);
      
      //plat = plat.toFixed(2).replace(/(\d{1,3}(?=(\d{3})+\,\d))/g,"\$1 ");
      //plat = plat.replace(/[^0-9|\.|,]/gi, "");
      //summa = prepareNumber(summa);      
      //tf.summa.value = summa;      
    	//document.getElementById('month_pay').innerHTML = '('+ps+'|'+x+'|'+y+'|z'+z+'|ap'+ap+'|'+kp+'|'+') '+plat;
    	
      if(type == 'auto'){
        document.getElementById('auto_month_pay').innerHTML = plat00;
        document.getElementById('auto_fee').innerHTML = kp;
      }
      if(type == 'express'){
        document.getElementById('express_month_pay').innerHTML = plat00;
        document.getElementById('express_fee').innerHTML = kp;
      }
  }
  
  function SumChanged(type) {
      if (type == 'express') {
		
        var tf = document.getElementById('express');
		var summa = parseFloat(tf.summa.value);
		var maxmonths = 0;
		
		if (summa >= 10000) {
			if (summa <= 100000) {
				maxmonths = 24;
			}
			else if (summa <= 300000) {
				maxmonths = 36;
			}
		}

		if (maxmonths > 0) {
			// Get the dropdown element
	        var m = document.getElementById('express').elements['months'];
			var savedSelected = m.selectedIndex;
			// Erase all elements
			m.length = 0;
			// Fill it again
			for (i = 3; i <= maxmonths; i++){
				m.options[m.options.length]=new Option(i, i, false, false)
			}
			// Restore previously selected element
			if (savedSelected <= m.options.length-1) {
				m.selectedIndex = savedSelected;
			}
			else {
				m.selectedIndex = m.options.length-1;
			}
			Calc('express');
		}
		else {
	        document.getElementById('express_month_pay').innerHTML = '--';
    	    document.getElementById('express_fee').innerHTML = '--';
		}
	  }
	  
  }


  function ClearFields() {
  	tf.quantity.value = 1;
  }