text: XOR operation leaves only uncommon characters in the ans variable
code: var ans = a1 ^ a2 ; var i = 0 ; while ( i < 26 ) { if ( ans % 2 == 1 ) { document . write ( String . fromCharCode ( ' ' . charCodeAt ( 0 ) + i ) ) ; } ans = parseInt ( ans / 2 ) ; i ++ ; } }