Wrong count is also accepting in Jquery and accepting keywords any where

Wrong count is also accepting in Jquery and accepting keywords any where

Requirement: textbox limit: 25characters, max limit:40char allow 
IF text contains {State},count for {State} only is 16, 
{City} count 14, {St}=2,{Zip}=5
 
Problem:
I have written JQuery code for this (below code) but it accepts
1.25chars={City}123456789—correct
2.25charcters=1234567891245678{City}-wrong- but it also accepting this one
3.25-chareacters=123456789123456789{City}---wrong- but it also accepting this one
 

 

1 dropdown:MainContent_ddlSelectAdLine Options: HeadLine
 
1 Textbox: MainContent_txtAdline onkeyup=”
<input name="ctl00$MainContent$txtAdline" type="text" id="MainContent_txtAdline" onkeyup="getBatch(event);" style="border-style:Inset;width:85%;" maxlength="50">
 
1 Span: MainContent_lblCount—for charcters Counting
50
 
Jquery Code: 
 
function getBatch(e) {
debugger;
var len=0; 
var cnt = $("#MainContent_txtAdline").val();
var count = $("#MainContent_txtAdline").val().length;
 
if (cnt.indexOf("{City}") > -1) 
{len = 16;$("#MainContent_lblCount").html(16);count = count-6+len}
else if (cnt.indexOf("{State}") > -1) { len = 14; count = count - 7 + len }
else if (cnt.indexOf("{St}") > -1) { len = 2; count = count - 4 + len }
else if(cnt.indexOf("{Zip}")>-1){len=5; count=count-5+len}
else { len = 0; count=count+len} 

 
if (count <= 0) {
count = 0;
}

var ddlslectedText = $("#MainContent_ddlSelectAdLine option:selected").text();
if (ddlslectedText == "HeadLine") {
if (cnt.indexOf("{City}") > -1)
{ $("#MainContent_txtAdline").attr('maxlength', '30'); }
else if (cnt.indexOf("{State}") > -1) 
{ $("#MainContent_txtAdline").attr('maxlength', '30'); }
else if (cnt.indexOf("{St}") > -1) 
{ $("#MainContent_txtAdline").attr('maxlength', '30'); }
else if (cnt.indexOf("{Zip}") > -1) 
{ $("#MainContent_txtAdline").attr('maxlength', '40'); }
else { $("#MainContent_txtAdline").attr('maxlength', '40'); }

 

if (count > 25) {
$("#MainContent_lblCount").html(count).css('color', '#CC0000');

}
else { $("#MainContent_lblCount").html(count).css('color', '#000000'); }
}

}