#include<bits/stdc++.h>
using namespace std;

int main(){
int a,s,d,f,j;
cin>>a;
s=a%10;
d=a/10%10;
f=a/100;
j=s+d+f;
cout<<j;
	return 0;
}

/**************************************************************
	Problem: 1027
	User: shenyue
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/