#include <iostream>
#include <string>
using namespace std;

int main(){
    string str; cin >> str;
    int sum = 0;
    for(int i = 0; i < str.size(); i++){
        if(str[i] == '1') sum += 1;
        else if(str[i] == '2') sum += 2;
        else if(str[i] == '3') sum += 3;
        else if(str[i] == '4') sum += 4;
        else if(str[i] == '5') sum += 5;
        else if(str[i] == '6') sum += 6;
        else if(str[i] == '7') sum += 7;
        else if(str[i] == '8') sum += 8;
        else if(str[i] == '9') sum += 9;
    }
    cout << sum << endl;
    return 0;
}