#include<bits/stdc++.h>
using namespace std;
int main() {
    int x,a,b,c;
    cin>>x;
    a=x%10;
    b=x/10%10;
    c=x/100;
    cout<<a+b+c;
}
/**************************************************************
	Problem: 1716
	User: chenjiahui
	Language: C++
	Result: Accepted
	Time:30 ms
	Memory:2072 kb
****************************************************************/