```go
package main

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

type Point struct {
	x int
	y int
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Scan()
	n, _ := strconv.Atoi(scanner.Text())
	points := make([]Point, 0, n)
	for i := 0; i < n; i++ {
		scanner.Scan()
		x, _ := strconv.Atoi(scanner.Text())
		scanner.Scan()
		y, _ := strconv.Atoi(scanner.Text())
		points = append(points, Point{x, y})
	}
	maxDist := 0.0
	for i := 0; i < n; i++ {
		for j := i + 1; j < n; j++ {
			dx := points[i].x - points[j].x
			dy := points[i].y - points[j].y
			dist := math.Sqrt(float64(dx*dx + dy*dy))
			if dist > maxDist {
				maxDist = dist
			}
		}
	}
	fmt.Printf("%.10f\n", maxDist)
}
```