# usage: xor.py file1 file2 offset1 offset2

import sys

with file( sys.argv[1], 'rb' ) as one:
    with file( sys.argv[2], 'rb' ) as two:
        one.seek( int( sys.argv[3] ) )
        two.seek( int( sys.argv[4] ) )
        for c in one.read():
            try:
                sys.stdout.write( chr( ord( c ) ^ ord( two.read( 1 ) ) ) )
            except:
                break