#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,g,s,b,h=0;
	scanf("%d",&x);
	g=x%10;
	s=x/10%10;
	b=x/100;
	h=g+s+b;
	printf("%d",h);
	return 0;
}
/**************************************************************
	Problem: 1027
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2076 kb
****************************************************************/