#include<bits/stdc++.h>
using namespace std;
int p;
int main(){
    string s;
    getline(cin,s);
    for(int i=0;i<s.size();i++){
    	p=p+(s[i]-48);
    }
    cout<<p;
	return 0;
}   
/**************************************************************
	Problem: 1115
	User: suzihang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/