#include<bits/stdc++.h>
using namespace std;
 
int main(){
    int x,s,a,b,c;
    cin>>x;
    a=x%10;
    b=x/10%10;
    c=x/100%10;
    s=a+b+c;
    cout<<s;
    return 0;
}
/**************************************************************
	Problem: 1027
	User: wuzhijing
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/