#include<bits/stdc++.h>
using namespace std;
int main(){
	int r,m,a,b,c;
	cin>>r;
	a=r%10;
	b=r/10%10;
	c=r/100;
	m=a+b+c;
	cout<<m;
	
}

/**************************************************************
	Problem: 1716
	User: zhengzihao3
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/