#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,s,a,b,c;
    cin>>x;
    a=x%10;
    b=x/10%10;
    c=x/100;
    s=a+b+c;
    cout<<s;
	
	return 0;
}
/**************************************************************
	Problem: 1317
	User: chenyaohuo
	Language: C++
	Result: Wrong Answer
****************************************************************/