Chef and Amazingness of Numbers

Chef defined amazingness of a number n as follows. Let array a denote the decimal representation of n. amazingness of n is defined by following pseudo code. amazingness(a) { set s; int ans = 0; for ( int i = 0; i n counting from most signficant digit (left to right). if (val not present in set s before) { ans += val; add val to set s } } } return ans; } Given two integers L, R. Find out t