function validatePresenterApplication(){
	with (document.main){
		var problem = 0
		var message = ""
		if (presenter_surname.value==""){
			problem++
			message+="\nPresenter surname is required."
		}				
		if (!verifyEmail(email.value)){
			problem++
			message+="\nA valid email address is required."
		}					
		if (problem > 0){
			alert(message);
			return false;
		}
		else{
			return true;
		}
	}
}

function validateConfRegistration(){
	with (document.main){
		var problem = 0
		var message = ""
		if (name.value==""){
			problem++
			message+="\nFirst name is required."
		}				
		if (surname.value==""){
			problem++
			message+="\nSurname is required."
		}	
		if (home_phone.value==""){
			problem++
			message+="\nHome telephone is required."
		}	
		if (!verifyEmail(email.value)){
			problem++
			message+="\nA valid email address is required."
		}					
		if (problem > 0){
			alert(message);
			return false;
		}
		else{
			return true;
		}
	}
}

function validateContact(){
	with (document.main){
		var problem = 0
		var message = ""
		if (First_Name.value==""){
			problem++
			message+="\nFirst name is required."
		}		
		if (Last_Name.value==""){
			problem++
			message+="\nLast name is required."
		}		
		if (!verifyEmail(Email.value)){
			problem++
			message+="\nA valid email address is required."
		}				
		if (problem > 0){
			alert(message);
			return false;
		}
		else{
			return true;
		}
	}
}

function verifyEmail(addr) { 
    var atPos = addr.indexOf('@'); 
    var dotPos = addr.lastIndexOf('.') 
    if (atPos>0 && dotPos>atPos+1) return true; 
    else
    	return false;
} 

function left(str, n){
	if (n <= 0)
	    return "";
	else if (n > String(str).length)
	    return str;
	else
	    return String(str).substring(0,n);
}

function right(str, n){
    if (n <= 0)
       return "";
    else if (n > String(str).length)
       return str;
    else {
       var iLen = String(str).length;
       return String(str).substring(iLen, iLen - n);
    }
}