package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
)

func main() {
	reader := bufio.NewReader(os.Stdin)
	var T int
	if _, err := fmt.Fscan(reader, &T); err != nil {
		return
	}
	for i := 0; i < T; i++ {
		var n float64
		fmt.Fscan(reader, &n)
		ans := math.Cos(math.Pi/(4*n)) / math.Sin(math.Pi/(2*n))
		fmt.Printf("%.9f\n", ans)
	}
}