#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,h=0;
    cin>>n;
    while(n>0){
    	h=h+n%10;
    	n=n/10;
    }
    cout<<h;
}
/**************************************************************
	Problem: 1960
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/