var value_isValid = true;

    function ValidateRequired(cont) {

        if (cont.value == null || cont.value == "") {

            cont.style.border = "solid 1px red";

            value_isValid = value_isValid && false;

        }

        else {

            cont.style.border = "";

            value_isValid = value_isValid && true;

        }

    }



    function ValidateEmail(cont) {

        var apos = cont.value.indexOf("@");

        var dotpos = cont.value.lastIndexOf(".");

        if (apos < 1 || dotpos - apos < 2) {

            cont.style.border = "solid 1px red";

            value_isValid = value_isValid && false;

        }

        else {

            cont.style.border = "";

            value_isValid = value_isValid && true;

        }

    }



    function Validatenews() {

        value_isValid = true;

        ValidateRequired(document.getElementById('nameNews'));

        ValidateEmail(document.getElementById('emailNews'));

       if (value_isValid)

        { return true; }

        else

        { return false; }

    }

    

    function mailToNews() {

        if (Validatenews()) { 

            document.getElementById('errorNews').style.display = "none";

        }

        else {

            document.getElementById('errorNews').style.display = "block";

            return false; 

        }

    }
	
function Validatefirend() {

        value_isValid = true;

        ValidateEmail(document.getElementById('sender email'));
		
		ValidateEmail(document.getElementById('reciever email'));

       if (value_isValid)

        { return true; }

        else

        { return false; }

    }

    

    function tellToFriend() {

        if (Validatefirend()) { 

            document.getElementById('errorFriend').style.display = "none";

        }

        else {

            document.getElementById('errorFriend').style.display = "block";

            return false; 

        }

    }

function show(id){ 
	document.getElementById('Form').style.display="block";
 }