// No.289 数字を全て足そう

package main

import (
	"fmt"
	"strconv"
	"strings"
)

func main() {
	var s string
	fmt.Scan(&s)

	sum := 0
	for _, v := range strings.Split(s, "") {
		n, _ := strconv.Atoi(string(v))
		sum += n
	}
	fmt.Println(sum)
}