#include<bits/stdc++.h>
using namespace std;
int main(){
	int x,s,a,b,c;
	scanf("%d",s);
	a=x%10;
	b=x/10%10;
	c=x/100;
	s=a+b+c; 
	printf("%d",s);
} 

/**************************************************************
	Problem: 1027
	User: zhangyilei
	Language: C++
	Result: Runtime Error
****************************************************************/