#include<bits/stdc++.h>
using namespace std;
int main()
{
long long i;
int a=0;
cin>>i;
while(i!=0)
{
a=a+i%10;
i=i/10;
}
cout<<a;
return 0;
}
/**************************************************************
	Problem: 1119
	User: BUDIN666
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/