#include<bits/stdc++.h>
using namespace std;
int main()
{
long long n,i=0;
cin>>n;
while(n){
    i=i+n%10;
    n/=10;
}
cout<<i;
return 0;
}
/**************************************************************
	Problem: 1119
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/