#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>

#define rep(i,n) for(i=0; i<n; ++i)
#define in(a) cin >> a
#define out(a,b) cout << a << b
using namespace std;
using lint = long long;

int main(void){
    int i, j, n, m, k, cnt = 0;
    string s;
    in(s);
    int nums = '9' - '0';
    rep(i,s.size()){
        int dis = s[i]-'0';
        if(0<=dis&&dis<=nums)   cnt+=dis;
    }
    out(cnt,endl);
    return 0;
}