#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,a,b,c,s=0;
	cin>>x;
	a=x/100;
	b=x/10%10;
	c=x%10;
	s=a+b+c;
	cout<<s;	
}
/**************************************************************
	Problem: 1027
	User: fhjdghj
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/