#include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<algorithm>
#include<vector>
#include<math.h>
#include<stack>
using namespace std;
int main(void){
    string S; cin >> S;
    int cnt = 0;
    for(int i = 0; i < S.size(); i++){
        if(S[i] -'0' < 10){
        cnt += S[i] -'0';
        }
    }
    cout << cnt << endl;
    return 0;
}