#include <bits/stdc++.h>
using namespace std;
int main(){
	int x,a,b,c,d=0;
	cin>>x;
	a=x%10;
	b=x/10%10;
	c=x/100;
	d=a+b+c;
	cout<<d; 
	
	
	
	}
/**************************************************************
	Problem: 1027
	User: zhuangwenya
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/