#include<iostream>
using namespace std;
int main(){
    int n,a,b,c;
    cin>>n;
    a=n/100;
    b=n/10%10;
    c=n%10;
    n=a+b+c;
    cout<<n; 
}
/**************************************************************
	Problem: 1733
	User: linmiaoling
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/