package main

import (
	"fmt"
	"strconv"
)

func main() {
	var S string
	var sum int
	fmt.Scanln(&S)
	for _, r := range S {
		i, err := strconv.Atoi(string(r))
		if err != nil {
			continue
		}
		sum += i
	}
	fmt.Println(sum)
}