DouKaku?

import sys

def main():
    if not len(sys.argv) == 2:
        sys.stderr.write("usage: input_file_name\n")
        return
    a = None
    for line in (line.rstrip() for line in open(sys.argv[1])):
        print line
        if a is None: # first line
            a = list(line)
        else: # after second line
            for i in xrange(1, len(a), 2):
                if line[i] == '-':
                    a[i - 1], a[i + 1] = a[i + 1], a[i - 1]
    print "".join(a)

if __name__ == '__main__':
    main()