func main()
	var N: int :: cui@input().toInt(&)
	var k: int :: (N + 1) / 3 * 2 + (N % 3 = 1 ?(1, 0))
	var A: []int :: #[N]int
	var B: []int :: #[N]int
	var C: []int :: #[N]int
	for i(0, N - 1)
		var _: [][]char :: cui@input().split(" ")
		do A[i] :: _[0].toInt(&)
		do B[i] :: _[1].toInt(&)
		do C[i] :: (A[i] + (B[i] * (k - 1))) * 10 ^ 5 + i
	end for
	do C.sort()
	var AA: []int :: #[k]int
	var BB: []int :: #[k]int
	for i(0, k - 1)
		var id: int :: C[i] % 10 ^ 5
		do AA[i] :: A[id]
		do BB[i] :: B[id]
	end for
	do BB.sort()
	do BB.reverse()
	var ans: int
	for i(0, k - 1)
		do ans :+ AA[i] + BB[i] * i
	end for
	do cui@print("\{ans}\n")
end func