#include<iostream>
#include<cstring>
using namespace std;
int main(){
	
	int a[11];
	string s;
	memset(a,0,sizeof(a));
	
	cin>>s;
	
	int n=s.length();
	
	
	for(int i=0;i<n;i++){
		a[i]=s[i]-'0';
	}
	
	int sum=0;
	
	for(int i=0;i<n;i++)
	 	sum=sum+a[i];
	 	
	cout<<sum<<endl;
	
	
}
/**************************************************************
	Problem: 1119
	User: admin
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2076 kb
****************************************************************/