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


/**************************************************************
	Problem: 1119
	User: cx001
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/