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

/**************************************************************
	Problem: 1027
	User: wqc123
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/