#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1e9+7;
int sum;
main(){
    string s;
    cin >> s;
    for(char c:s)if(c >= '1' && c <= '9')sum += c-'0';
    cout << sum;
}