#agc044e. [agc044_e]Random Pawn

[agc044_e]Random Pawn

Problem Statement

You are playing a game and your goal is to maximize your expected gain. At the beginning of the game, a pawn is put, uniformly at random, at a position pin1,2,dots,Np\\in\\{1,2,\\dots, N\\}. The NN positions are arranged on a circle (so that 11 is between NN and 22).

The game consists of turns. At each turn you can either end the game, and get ApA_p dollars (where pp is the current position of the pawn), or pay BpB_p dollar to keep playing. If you decide to keep playing, the pawn is randomly moved to one of the two adjacent positions p1p-1, p+1p+1 (with the identifications 0=N0 = N and N+1=1N+1=1).

What is the expected gain of an optimal strategy?

Note: The "expected gain of an optimal strategy" shall be defined as the supremum of the expected gain among all strategies such that the game ends in a finite number of turns.

Constraints

  • 2leNle200,0002 \\le N \\le 200,000
  • 0leAple10120 \\le A_p \\le 10^{12} for any p=1,ldots,Np = 1,\\ldots, N
  • 0leBple1000 \\le B_p \\le 100 for any p=1,ldots,Np = 1, \\ldots, N
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

NN A1A_1 A2A_2 cdots\\cdots ANA_N B1B_1 B2B_2 cdots\\cdots BNB_N

Output

Print a single real number, the expected gain of an optimal strategy. Your answer will be considered correct if its relative or absolute error does not exceed 101010^{-10}.


Sample Input 1

5
4 2 6 3 5
1 1 1 1 1

Sample Output 1

4.700000000000

Sample Input 2

4
100 0 100 0
0 100 0 100

Sample Output 2

50.000000000000

Sample Input 3

14
4839 5400 6231 5800 6001 5200 6350 7133 7986 8012 7537 7013 6477 5912
34 54 61 32 52 61 21 43 65 12 45 21 1 4

Sample Output 3

7047.142857142857

Sample Input 4

10
470606482521 533212137322 116718867454 746976621474 457112271419 815899162072 641324977314 88281100571 9231169966 455007126951
26 83 30 59 100 88 84 91 54 61

Sample Output 4

815899161079.400024414062