import std.algorithm, std.array, std.container, std.range;
import std.string, std.conv;
import std.math, std.bigint, std.bitmanip, std.random;
import std.stdio, std.typecons;

const auto repeat = 10 ^^ 6;

void main()
{
  auto n = readln.chomp.to!int;
  auto ai = readln.split.map!(to!int).array;
  auto bi = readln.split.map!(to!int).array;

  auto r = 0;
  foreach (_; 0..repeat) {
    ai.randomShuffle;
    bi.randomShuffle;
    if (ai.zip(bi).count!("a[0] > a[1]") > n / 2)
      r += 1;
  }

  writefln("%f", r.to!real / repeat);
}