#include <bits/stdc++.h> 
using namespace std;
int main(){
    int n,a,b,c,d;
    cin>>n;
    a=n%10;
    b=n%100/10;
    c=n/100;
    d=a+b+c;
    cout<<d;
}
/**************************************************************
	Problem: 1716
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:35 ms
	Memory:2072 kb
****************************************************************/