#include<iostream>
using namespace std;
int main(){
	int x,g,s,b,n;
	cin>>n;
	g=n%10;
	s=n/10%10;
	b=n/100;
	cout<<g+s+b;
} 
/**************************************************************
	Problem: 1027
	User: wngjinming
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/