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