#include <iostream>
#include <fstream>
#include <algorithm>
#include <bits/stdc++.h>
#define zero '0'

using namespace std;


int main(){
    ifstream cin;
    ofstream cout;
    cin.open("input.txt");
    cout.open("output.txt");
    string st = "";
    vector <int> a;
    int pr = 0;
    int cn = 0;
    cin >> st;
    pr = st[0]-zero;
    cn++;
    //cout << st.length() << endl;
    for (int i=1; i<st.length(); i++){
        //cout << pr << endl;
        if (cn==pr+1){
                a.push_back(pr);
                //cout << st[i] << " ";
                pr = st[i]-zero;
                cn=0;
        }
        if (pr!=(st[i]-zero)){
            //cout << pr << endl;
            //cout << cn << endl;
            if (cn==pr+1){
                a.push_back(pr);
                //cout << st[i] << " ";
                pr = st[i]-zero;
                cn=0;
            }else{
                cout << -1;
                return 0;
            }
        }
        cn++;
        //cout << endl;
    }

    if (cn==pr+1){
        a.push_back(pr);
        //cout << st[i] << " ";
        pr = st[st.size()-1]-zero;
        cn=0;
    }else{
        cout << -1;
        return 0;
    }
    st ="";
    for (int i = 0; i<a.size(); i++){
//        cout << a[i];
        st += a[i]+'0';
    }
    int zz = atoi(st.c_str());
    if (zz<=1000000){
        cout << zz;
    }else{
        cout << "-1";
    }
    return 0;
}