#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,s,a,b,c;
	cin>>x;
	a=x%10;
	b=x/10%10;
	c=x/100; 
	s=a+b+c;
	cout<<s;
	return 0;
/**************************************************************
	Problem: 1027
	User: zhenghaoxuan
	Language: C++
	Result: Compile Error
****************************************************************/