#include <bits/stdc++.h>//万能头 using namespace std; int n; int main() { cin>>n;//输入 printf("%d",n/10%10+n%10+n/100);//个十百位之和 return 0;//养成好习惯 }

#include<bits/stdc++.h> 
using namespace std;
int main(){
	int m,s,d,f,g;
	cin>>m;
	s=m/100;
	d=m%100/10;
	f=m%100%10;
	g=s+d+f;
	cout<<g;
	return 0;
}