func main()
	var n: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	
	var ans: int :: 0
	for i(0, n - 1)
		for j(0, n - 1)
			if(a[j] = a[i] - 1)
				skip i
			end if
		end for
		do ans :+ a[i]
	end for
	do cui@print("\{ans}\n")
end func