def main(io) n = io.get p = Array.new(n, 0) io.put_e 0 if n == 1 (0...n//2).each do |i| if i.even? p[i] = i+1 p[-1-i] = n-i else p[i] = n-i p[-1-i] = i+1 end end p[n//2] = n//2+1 if n.odd? r = n p.each_cons_pair do |i, j| r += i.to_i64*j end io.put r end class ProconIO def initialize @buf = [] of String @index = 0 end def get(k : T.class = Int32) forall T get_v(k) end def get(*ks : T.class) forall T ks.map { |k| get_v(k) } end macro define_getn {% for i in (2..9) %} def get{{i}}(k : T.class = Int32) forall T get({% for j in (1..i) %}k{% if j < i %}, {% end %}{% end %}) end {% end %} end define_getn def get_a(n : Int, k : T.class = Int32) forall T Array.new(n) { get_v(k) } end def get_c(n : Int, k : T.class = Int32) forall T get_a(n, k) end def get_c(n : Int, *ks : T.class) forall T a = Array.new(n) { get(*ks) } ks.map_with_index { |_, i| a.map { |e| e[i] } } end macro define_getn_c {% for i in (2..9) %} def get{{i}}_c(n : Int, k : T.class = Int32) forall T get_c(n, {% for j in (1..i) %}k{% if j < i %}, {% end %}{% end %}) end {% end %} end define_getn_c def get_m(r : Int, c : Int, k : T.class = Int32) forall T Array.new(r) { get_a(c, k) } end def put(*vs) vs.each.with_index do |v, i| put_v(v) print i < vs.size - 1 ? " " : "\n" end end def put_e(*vs) put(*vs) exit end private def get_v(k : Int32.class); get_token.to_i32; end private def get_v(k : Int64.class); get_token.to_i64; end private def get_v(k : String.class); get_token; end private def get_token if @buf.size == @index @buf = read_line.split @index = 0 end v = @buf[@index] @index += 1 v end private def put_v(vs : Enumerable) vs.each_with_index do |v, i| print v print " " if i < vs.size - 1 end end private def put_v(v) print v end end main(ProconIO.new)