#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y,z,n;
    cin>>n;
    x=n%10;
    y=n/10%10;
    z=n/100;
    cout<<x+y+z;
}
/**************************************************************
	Problem: 1716
	User: baizhoudeyueguang
	Language: C++
	Result: Accepted
	Time:28 ms
	Memory:2072 kb
****************************************************************/