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

int main() {
    
    string s;
    vector<long> list;
    cin >> s;
    for(int i = 0; i < s.size(); i++){
        try {
            list.push_back(stoi(s.substr(i,1)));
        } catch (const std::invalid_argument& e) {
        }
    }
    if(list.size() == 0){
        cout << 0 << "\n";
    }else{
        for(int i = 0; i < list.size(); i++){
            cout << list[i];
        }
    }
    cout << "\n";
    
    return 0;
}