func main()
	var n: int :: cui@inputInt()
	var k: int :: cui@inputInt()
	var a: []int :: #[n]int
	for i(0, n - 1)
		do a[i] :: cui@inputInt()
	end for
	do a.sort()
	
	var b: []int :: #[n - 1]int
	for i(0, n - 2)
		do b[i] :: a[i + 1] - a[i]
	end for
	do b.sort()
	do b.reverse()
	
	var ans: int :: a[n - 1] - a[0]
	for i(0, k - 2)
		do ans :- b[i]
	end for
	do cui@print("\{ans}\n")
end func