#include <iostream>

using namespace std;

int sum_str(char *str)
{
        int sum = 0;

        for(int i = 0;i < str[i] != '\0';i++){
                if((str[i] - '0') >= 0 && (str[i] - '0') <= 9)
                        sum += (str[i] - '0');
        }

        return sum;
}

int main()
{
        char str[256];

        cin >> str;

        cout << sum_str(str) << endl;

        return 0;
}