RU-ALLRUSSIAN 1985 Problem 7

In the diagram below a, b, c, d, e, f, g, h, i, j are distinct positive integers and each (except a, e, h and j) is the sum of the two numbers to the left and above. For example, $\mathrm{b} = \mathrm{a} + \mathrm{e}$ , $\mathrm{f} = \mathrm{e} + \mathrm{h}$ , $\mathrm{i} = \mathrm{h} + \mathrm{j}$ . What is the smallest possible value of d?

h i e f g a b c d