#include<bits/stdc++.h> 
using namespace std;
int n,m,g,s,b;
int main(){
    cin>>n;
    g=n%10;
    s=n/10%10;
    b=n/100;
    m=g+s+b;
    printf("%d",m); 
}
/**************************************************************
	Problem: 1716
	User: chenyichuen
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/