package main

import "fmt"
import "strconv"
import "strings"

func main() {
	var s string
	fmt.Scan(&s)
	sum := 0
	for _, v := range strings.Split(s, "") {
		if i, err := strconv.Atoi(v); err == nil {
			sum = sum + i
		}
	}
	fmt.Println(sum)
}