def solve(io)
  n = io.get
  c, d = io.get2_c(n, Int64)

  e = [] of GraphW::Edge(Int64)
  n.times do |u|
    e << GraphW::Edge(Int64).new(u, n, c[u])
  end
  (1...n).each do |u|
    e << GraphW::Edge(Int64).new(u-1, u, d[u])
  end

  e.sort_by! { |ei| ei.wt }
  uf = UnionFind.new(n+1)
  r = 0_i64
  e.each do |ei|
    next if uf.same?(ei.src, ei.dst)
    uf.unite(ei.src, ei.dst)
    r += ei.wt
    break if uf.count_forests == 1
  end

  io.put c.sum + r
end

class ProconIO
  def initialize(@ins : IO = STDIN, @outs : IO = STDOUT)
    @buf = IO::Memory.new("")
  end

  def get(k : T.class = Int32) forall T
    get_v(k)
  end

  macro define_get
    {% for i in (2..9) %}
      def get({{ *(1..i).map { |j| "k#{j}".id } }})
        { {{ *(1..i).map { |j| "get(k#{j})".id } }} }
      end
    {% end %}
  end
  define_get

  macro define_getn
    {% for i in (2..9) %}
      def get{{i}}(k : T.class = Int32) forall T
        get({{ *(1..i).map { "k".id } }})
      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

  macro define_get_c
    {% for i in (2..9) %}
      def get_c(n : Int, {{ *(1..i).map { |j| "k#{j}".id } }})
        a = Array.new(n) { get({{ *(1..i).map { |j| "k#{j}".id } }}) }
        { {{ *(1..i).map { |j| "a.map { |e| e[#{j-1}] }".id } }} }
      end
    {% end %}
  end
  define_get_c

  macro define_getn_c
    {% for i in (2..9) %}
      def get{{i}}_c(n : Int, k : T.class = Int32) forall T
        get_c(n, {{ *(1..i).map { "k".id } }})
      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

  macro define_put
    {% for i in (1..9) %}
      def put({{ *(1..i).map { |j| "v#{j}".id } }}, *, delimiter = " ")
        {% for j in (1..i) %}
          print_v(v{{j}}, delimiter)
          {% if j < i %}@outs << delimiter{% end %}
        {% end %}
        @outs.puts
      end
    {% end %}
  end
  define_put

  def put_e(*vs)
    put(*vs)
    exit
  end

  def put_f(*vs)
    put(*vs)
    @outs.flush
  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 : UInt32.class); get_token.to_u32; end
  private def get_v(k : UInt64.class); get_token.to_u64; end
  private def get_v(k : Float64.class); get_token.to_f64; end
  private def get_v(k : String.class); get_token; end

  private def get_token
    loop do
      token = @buf.gets(' ', chomp: true)
      break token unless token.nil?
      @buf = IO::Memory.new(@ins.read_line)
    end
  end

  private def print_v(v, dlimiter)
    @outs << v
  end

  private def print_v(v : Enumerable, delimiter)
    v.each_with_index do |e, i|
      @outs << e
      @outs << delimiter if i < v.size - 1
    end
  end
end

struct Int
  def cdiv(b : Int)
    (self + b - 1) // b
  end

  def bit?(i : Int)
    bit(i) == 1
  end

  def set_bit(i : Int)
    self | (self.class.new(1) << i)
  end

  def reset_bit(i : Int)
    self & ~(self.class.new(1) << i)
  end

  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "0.34.0") < 0 %}
    def bit_length : Int32
      x = self < 0 ? ~self : self

      if x.is_a?(Int::Primitive)
        Int32.new(sizeof(self) * 8 - x.leading_zeros_count)
      else
        to_s(2).size
      end
    end
  {% end %}
end

struct Int32
  SQRT_MAX = 46_340_i32

  def isqrt
    m = SQRT_MAX
    r = (1_i32..SQRT_MAX).bsearch { |i| i**2 > self }
    r.nil? ? SQRT_MAX : r - 1
  end
end

struct Int64
  SQRT_MAX = 3_037_000_499_i64

  def isqrt
    r = (1_i64..SQRT_MAX).bsearch { |i| i**2 > self }
    r.nil? ? SQRT_MAX : r - 1
  end
end

struct Float64
  def near_zero?
    self.abs < EPSILON
  end
end

struct Number
  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "1.1.0") < 0 %}
    def zero?
      self == 0
    end

    def positive?
      self > 0
    end

    def negative?
      self < 0
    end
  {% end %}

  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "0.36.0") < 0 %}
    def self.additive_identity
      zero
    end

    def self.multiplicative_identity
      new(1)
    end
  {% end %}
end

class Array
  macro new_md(*args, &block)
    {% if !block %}
      {% for arg, i in args[0...-2] %}
        Array.new({{arg}}) {
      {% end %}
      Array.new({{args[-2]}}, {{args[-1]}})
      {% for arg in args[0...-2] %}
        }
      {% end %}
    {% else %}
      {% for arg, i in args %}
        Array.new({{arg}}) { |_i{{i}}|
      {% end %}
      {% for block_arg, i in block.args %}
        {{block_arg}} = _i{{i}}
      {% end %}
      {{block.body}}
      {% for arg in args %}
        }
      {% end %}
    {% end %}
  end
end

macro min_u(a, b)
  {{a}} = Math.min({{a}}, {{b}})
end

macro max_u(a, b)
  {{a}} = Math.max({{a}}, {{b}})
end

macro zip(a, *b, &block)
  {{a}}.zip({{*b}}) {{block}}
end

class UnionFind
  def initialize(@n : Int32)
    @s = @n
    @p = Array.new(@n, @s)
    @cf = @n
    @cn = Array.new(@n, 1)
  end

  def unite(u : Int, v : Int)
    pu, pv = subst(u), subst(v)
    if pu != pv
      @p[pv] = pu
      @cf -= 1
      @cn[pu] += @cn[pv]
    end
    pu != pv
  end

  def subst(u : Int) : Int32
    @p[u] == @s ? u.to_i32 : (@p[u] = subst(@p[u]))
  end

  def same?(u : Int, v : Int)
    subst(u) == subst(v)
  end

  def count_forests
    @cf
  end

  def count_nodes_of(u : Int)
    @cn[subst(u)]
  end


  @p : Array(Int32)
  @cn : Array(Int32)
end

require "bit_array"

class Graph
  alias Node = Int32

  def initialize(@size : Node)
    @g = Array(Array(Node)).new(@size) { [] of Node }
  end

  getter size : Int32

  delegate :[], to: @g

  def add_edge(u : Node, v : Node)
    @g[u] << v
  end

  def add_edge_b(u : Node, v : Node)
    @g[u] << v
    @g[v] << u
  end

  def bfs(u : Node)
    b = BitArray.new(@size)
    yield u, -1
    b[u] = true
    q = Deque.new([u])
    until q.empty?
      v = q.shift
      @g[v].each do |w|
        next if b[w]
        yield w, v
        b[w] = true
        q.push(w)
      end
    end
  end
end

class GraphW(T)
  alias Node = Int32

  struct Edge(T)
    def initialize(@src : Node, @dst : Node, @wt : T)
    end

    getter src : Node, dst : Node

    getter wt : T
  end
      
  def initialize(@size : Node, @inf = 10**9)
    @g = Array(Array(Edge(T))).new(@size) { [] of Edge(T) }
  end

  getter size : Int32

  getter inf : T

  delegate :[], to: @g

  def add_edge(u : Node, v : Node, wt : T)
    @g[u] << Edge.new(u, v, wt)
  end

  def add_edge_b(u : Node, v : Node, wt : T)
    @g[u] << Edge.new(u, v, wt)
    @g[v] << Edge.new(v, u, wt)
  end
end

class GraphM(T)
  alias Node = Int32

  def initialize(@size : Int32, @inf = 10**9)
    @g = Array.new_md(@size, @size, @inf)
    @size.times do |i|
      @g[i][i] = T.zero
    end
  end

  getter size : Int32

  getter inf : T

  delegate :[], to: @g

  def add_edge(u : Node, v : Node, wt : T)
    @g[u][v] = wt
  end

  def add_edge_b(u : Node, v : Node, wt : T)
    @g[u][v] = @g[v][u] = wt
  end


  @g : Array(Array(T))
end

solve(ProconIO.new)