#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,s;
    cin>>x;
    s=x%10+x/10%10+x/100;
    cout<<s; 
     return 0;
}
/**************************************************************
	Problem: 1027
	User: panjinyan
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/