#!/usr/local/bin/perl

$totalcount=0;
$mistake=0;
$total=250;
while($totalcount<$total)
{
$no1=int(rand(time))%30;
$no2=int(rand(time))%30;

if($no1==0) 
{
$no1++;
}

if($no2==0) 
{
$no2++;
}
$plus=int(rand(time))%2;
$answer=0;
$wronglook=0;
GETINPUT:

if($plus==0)
{

$answer=$no1 + $no2;

print "$no1 + $no2 =";
if($no1>$no2)
{
$wronglook=$no1 - $no2;
}
else
{
$wronglook=$no2 - $no1;
}
}
else
{
$wronglook=$no1 + $no2;
if($no1>$no2)
{

print "$no1 - $no2 =";
$answer=$no1 - $no2;

}
else
{
print "$no2 - $no1 =";
$answer=$no2- $no1;
}
}



$userinput =  <STDIN>;
chomp($userinput);
if(length($userinput)==0)
{
print "Please input your answer\n";
goto GETINPUT;
}
$totalcount++;;

if($userinput == $answer) 
{
print "Great!!!! you did good job , the answer is Correct $userinput\n";
}
elsif($wronglook==$userinput)
{
print "Almost there!Let's take a second look at Operation sign is it + or -\n";
goto GETINPUT;

}
else
{
$mistake++;
print "wrong, the correct answer is ".$answer."\n";
}
if($totalcount%10==0)
{
$score=int(100-$mistake*100/$totalcount);
$left=$total-$totalcount;
$leftpercent=int($totalcount*100/400);
print "$totalcount problems done, ".$left." to go. finishing ".$leftpercent."\%. Score correct percentage rate ".$score."\%\n"; 
}

}