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