#include<iostream>
using namespace std;
int main( )
{
	int a,b,c,s;
	cin>>s;
	a=s%10;
	b=s/10%10;
	c=s/100;
	cout<<(a+b+c)<<endl;
} 
/**************************************************************
	Problem: 1027
	User: HUANGYIBO
	Language: C
	Result: Compile Error
****************************************************************/