#include<bits/stdc++.h>
using namespace std;
int x,a,b,c;
int main(){
	cin>>x;
	a=x/100; x%=100;
	b=x/10; x%=10;
	c=x;
	cout<<a+b+c;
	return 0;
}
/**************************************************************
	Problem: 1027
	User: zhangziang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/