package main

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

func main() {
	reader := bufio.NewReader(os.Stdin)

	fmt.Print("Enter a positive whole number n: ")
	text, _ := reader.ReadString('\n')
	n, _ := strconv.Atoi(strings.TrimSpace(text))

	total := 0
	for i := 1; i <= n; i++ {
		total += i
	}

	fmt.Printf("Sum from 1 to %d is %d\n", n, total)
	fmt.Println("Formula gives", n*(n+1)/2)
}