#include<bits/stdc++.h>
using namespace std;
int main(){
int  n;
cin>>n;
int  g,s,b;
  g=n/1%10;
  s=n/10%10;
  b=n/100%10;
  cout<<g+s+b;
 
return 0;	
	
} 
/**************************************************************
	Problem: 1027
	User: wangyousi
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/