Love AB Extension

function calc() {

first = document.loveform.name1.value.toUpperCase();
firstlength = document.loveform.name1.value.length;
second = document.loveform.name2.value.toUpperCase();
secondlength = document.loveform.name2.value.length;
var LoveCount=0;

for (Count=0; Count < firstlength; Count++) {
letter1=first.substring(Count,Count+1);
if (letter1=='L') LoveCount+=2;
if (letter1=='O') LoveCount+=2;
if (letter1=='V') LoveCount+=2;
if (letter1=='E') LoveCount+=2;
if (letter1=='Y') LoveCount+=3;
if (letter1=='O') LoveCount+=1;
if (letter1=='U') LoveCount+=3;
}

for (Count=0; Count < secondlength; Count++) {
letter2=second.substring(Count,Count+1);
if (letter2=='L') LoveCount+=2;
if (letter2=='O') LoveCount+=2;
if (letter2=='V') LoveCount+=2;
if (letter2=='E') LoveCount+=2;
if (letter2=='Y') LoveCount+=3;
if (letter2=='O') LoveCount+=1;
if (letter2=='U') LoveCount+=3;
}

amount=0;
if (LoveCount> 0) amount= 5-((firstlength+secondlength)/2)
if (LoveCount> 2) amount= 10-((firstlength+secondlength)/2)
if (LoveCount> 4) amount= 20-((firstlength+secondlength)/2)
if (LoveCount> 6) amount= 30-((firstlength+secondlength)/2)
if (LoveCount> 8) amount= 40-((firstlength+secondlength)/2)
if (LoveCount>10) amount= 50-((firstlength+secondlength)/2)
if (LoveCount>12) amount= 60-((firstlength+secondlength)/2)
if (LoveCount>14) amount= 70-((firstlength+secondlength)/2)
if (LoveCount>16) amount= 80-((firstlength+secondlength)/2)
if (LoveCount>18) amount= 90-((firstlength+secondlength)/2)
if (LoveCount>20) amount=100-((firstlength+secondlength)/2)
if (LoveCount>22) amount=110-((firstlength+secondlength)/2)

if (firstlength==0 || secondlength==0) amount= "Err";
if (amount < 0) amount= 0;
if (amount >99) amount=99;

document.loveform.output.value=amount+"%";