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