#include <bits/stdc++.h>

using namespace std;
typedef long long ll;



int main(){
    int n = 0;
    string s;
    cin >> s;
    for (int i = 0; i < s.size(); i++)
        if (isdigit(s[i]))
            n += s[i] - 48;
    cout << n << endl;
    return 0;

}