#include<bits/stdc++.h>
using namespace std;
int main(){
	int g,w,b,x,s;
	scanf("%d",&x);
	g=x%10;
	w=x/10%10;
	b=x/100;
	s=g+w+b;
	printf("%d",s);
	 
}

/**************************************************************
	Problem: 1027
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/