#include <bits/stdc++.h>
using namespace std;
int main(){
    int x,s,g,v,b;
    scanf("%d",&x);
    g=x%10;
    v=x/10%10;
    b=x/100%10;
    s=g+v+b;
    printf("%d",s);     
}
/**************************************************************
	Problem: 1716
	User: zhangyilei
	Language: C++
	Result: Accepted
	Time:26 ms
	Memory:2076 kb
****************************************************************/