function calculairport() {
	    var kurzeura = 25.92;
		var kurzpound = 35;
		var kurzusd = 17.50;
	    var finprice = "";
	    var numcars = 0;
	    var numc1 = 0;
        var numc2 = 0;
	    var numc3 = 0;
		var numc4 = 0;
		var numc5 = 0;
		var numc6 = 0;
		var numc7 = 0;
		var numc8 = 0;
		var nump1 = 0;
        var nump2 = 0;
	    var nump3 = 0;
		var nump4 = 0;
		var nump5 = 0;
		var nump6 = 0;
		var nump7 = 0;
	    var curdoc = document.getElementById("order_form");
	    var howmuch = curdoc.pocetcestujicich.value;
			
			document.getElementById("depa_den").disabled="disabled";
			document.getElementById("depa_mesic").disabled="disabled";
			document.getElementById("depa_rok").disabled="disabled";
			document.getElementById("depa_hodina").disabled="disabled";
			document.getElementById("depa_minuta").disabled="disabled";
	   
	    if (document.getElementById("dir1").checked == true) {
			nump1 = 550;
			nump2 = 890;
			nump3 = 1450;
			nump4 = 1800;
			nump5 = 2200;
			nump6 = 2800;
			nump7 = 4000;
	    }
	     else if (document.getElementById("dir2").checked == true) {
                        nump1 = 1100;
			nump2 = 1750;
			nump3 = 2800;
			nump4 = 3700;
			nump5 = 3900;
			nump6 = 5200;
			nump7 = 7600;                   
                
            document.getElementById("depa_den").disabled="";
			document.getElementById("depa_mesic").disabled="";
			document.getElementById("depa_rok").disabled="";
			document.getElementById("depa_hodina").disabled="";
			document.getElementById("depa_minuta").disabled="";
	    }
		
	    if ((howmuch > 0) && (howmuch < 50)) {
	    if (howmuch > 0 && howmuch < 5) {
				numc1 = 1;
			}
			else if ((howmuch > 4) && (howmuch < 9)) {
			    numc2 = 1;
			}
		
	       else if ((howmuch > 8) && (howmuch < 13)) {
                numc3 = 2;
	     	}
		
	   	   else if ((howmuch > 12) && (howmuch < 17)) {
			    numc4 = 2;
		    }
	       else if ((howmuch > 16) && (howmuch < 21)) {
		        numc5 = 1;

	    	}
	       else if ((howmuch > 20) && (howmuch < 29)) {
		     	numc6 = 2;	
	    	}
			
	else if ((howmuch > 28) && (howmuch < 50)) {
			    numc7 = 1;

						
		}
		}
            numcars = numc1 + numc2 + numc3 + numc4 + numc5 + numc6 + numc7;
	    
	    finprice = ((nump1 * numc1) + (nump2 * numc2) + (nump3 * numc3) + (nump4 * numc4) + (nump5 * numc5) + (nump6 * numc6) + (nump7 * numc7));
	    
	    prepocet = finprice / kurzeura;
	    finpriceeu = Math.round(prepocet);
	    
	    rozdil = finpriceeu - prepocet;
	    
		
		prepocetpound = finprice / kurzpound;
		finpricepound = Math.round(prepocetpound);
		
		prepocetusd = finprice / kurzusd;
		finpriceusd = Math.round(prepocetusd);
		
		
	    curdoc.cena.value = finprice + " CZK / " + finpriceeu + " EUR / " + finpricepound + " POUNDS / " + finpriceusd + " USD";
	    curdoc.pocetaut.value = numcars;
	    

	}