#include<bits/stdc++.h>
using namespace std;
int main()
{int n,g,s,b,q;
cin>>n;
g=n%10; 
s=n/10%10; 
b=n/100%10; 
q=n/1000;
cout<<g+s+b+q; 
 return 0;
 }

/**************************************************************
	Problem: 1390
	User: zxh001
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/