#include <bits/stdc++.h>
using namespace std;
int main(){
	long long N=0,a=0;
	cin>>N;
	while(N)
	{a+=N%10;
	N/=10;
	}
	cout<<a;
	return 0;
	}

/**************************************************************
	Problem: 1119
	User: ljl2
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/