#include <MsgBoxConstants.au3>

$title = "Similarity"
$a = InputBox($title, "Data 1")
$b = InputBox($title, "Data 2")
$n = 0
$la = StringLen($a)
$lb = StringLen($b)
$lc = ($la + $lb) / 2

If $la > $lb Then
   $l = $la
ElseIf $lb > $la Then
   $l = $lb
Else
   $l = $lc
EndIf

For $i = 0 To $l
   If ($a[$i] = $b[$i]) Then
	  $n = $n + 1
   EndIf
Next

$p = $n / $l * 100

MsgBox($MB_TOPMOST, $title, $a & @CRLF & $b & @CRLF & $title & ":" & @TAB & $p)

Exit