package main

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

func main() {
	var input string
	result := []int{}
	fmt.Scan(&input)
	n, _ := strconv.Atoi(input)
	result = append(result, n)
	for i := 0; i < 100; i++ {
		x := strconv.Itoa(result[i])
		y := strings.Split(x, "")
		var z int
		for _, a := range y {
			m, _ := strconv.Atoi(a)
	    	z += m
		}
		result = append(result, z)
	}
	fmt.Println(result[99])
}