#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

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