#include<iostream>
using namespace std;
int main()
{
int n,s=0;
cin>>n;
while(n!=0)
{
s+=n%10;
n/=10;
}
cout<<s<<endl;
return 0;
}

#include<iostream>
using namespace std;
int main()
{
    int a,sum=0;
    cin>>a;
    while(a!=0)
    {
        sum=sum+a%10;
        a=a/10;
    }
    cout<<sum<<endl;
}

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

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

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

}

#include<bits/stdc++.h>
using namespace std;
int main(){
    string a; getline(cin,a);
    int cnt=0;
    string::iterator it=a.begin();
    for(;it!=a.end();it++)
        cnt+=*it-48;
    cout<<cnt;
    return 0;
}