pyt txt div

def main():
    print '--start\n'

    f = open('test3.txt', 'r')
    f.close
    inp = f.read()

    inp = devide(inp, 30)
    #print inp

    f = open('out.txt', 'w')
    f.write(inp + '\n')
    f.close
    print '\n--stop'


def devide(st, n):  # n - cimbols in one line , n > 0
    if n <= 0:
        return -1
    else:
        i = 0
        end = len(st)
        for i in range(end):
            if i % n == 0:
                if st[i] != ' ':
                    j = i
                    while st[j] != ' ':
                        j = j - 1
                        if j < 0:
                            break
                    st = st[:j] + '\n' + st[j+1:]
        return st

main()