#include <bits/stdc++.h>
using namespace std;
int main(){
   int x,s,b,n,m; 
   cin>>x;
   b=x/1%10;
   n=x/10%10;
   m=x/100%10;
   s=b+n+m;
   cout<<s; 
return 0;
}

/**************************************************************
	Problem: 1027
	User: LYY001
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/