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