package main

import (
	"fmt"
	"math/big"
)

func main() {
	var n int
	fmt.Scanf("%d", &n)
	ans := big.NewRat(0, 1)
	for i := 0; i < n; i++ {
		r := new(big.Rat)
		fmt.Scan(r)
		ans.Add(ans, r)
	}
	fmt.Println(ans.FloatString(10))
}