#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,a,b,c;
    cin>>n;
    a=n%10;
    b=n/10%10;
    c=n/100;
    cout<<a+b+c;
}
/**************************************************************
	Problem: 1716
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:28 ms
	Memory:2072 kb
****************************************************************/