#include<bits/stdc++.h> 
using namespace std;
int main() {
    int x;
    cin >> x;
    int hundreds = x / 100;
    int tens = (x % 100) / 10;
    int units = x % 10;
    int sum = hundreds + tens + units;
    cout << sum << endl;
	return 0; 
}
/**************************************************************
	Problem: 1027
	User: huanghao
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2072 kb
****************************************************************/