#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <utility>

using namespace std;

int main(void){

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

    return 0;
}