#include <iostream>
using namespace std;
int main()
{
	int ge,shi,bai,x;
	cin >> x;
	cout << (x%10)+ ((x/10)%10)+(x/100);
	
}
/**************************************************************
	Problem: 1027
	User: xiaomingze
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/