#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%10;
    cout<<g+s+b+q;
}
/**************************************************************
	Problem: 1390
	User: zhangailin
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/