C++ :

#pragma GCC oprimize(2)
#include<bits/stdc++.h>
using namespace std;
string uke;
int kkk;
int main()
{
	cin>>uke;
	for(int s=0;s<uke.size();s++)
	kkk+=uke[s]-'0';
	cout<<kkk<<endl;
}