You are given a positive integer N. Assign one digit to each of the seven letters d, e, h, l, o, r, w so that the addition below holds.
hello+world=N
Here hello is the five digit number whose digits from the most significant one are h, e, l, l, o, and world is the five digit number whose digits from the most significant one are w, o, r, l, d. The digits assigned to the seven letters are pairwise different, and the leading digits h and w cannot be 0.