#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long a,b=0;
	cin>>a;
	while(a>0)
	{
		b+=a%10;
		a/=10;
	}
	cout<<b;
    return 0;
}

#include<bits/stdc++.h> using namespace std; int main() {

long long n,sum=0;
	cin>>n;
	while(n!=0)
	{
		sum+=n%10;
		n=n/10;
	} 
	cout<<sum;
return 0;

}