#include <iostream>
#include <cstdio>
using namespace std;

//char buff[1000005];

inline char opacne(char znak) {
    if(znak == '0')
        return '1';
    return '0';
}

void Zpracuj(string radek) {
    char akt = '0';
    int index = radek.length() - 1;
    while(index >= 0 && radek[index] != akt) {
        radek[index] = opacne(radek[index]);
        index--;
        akt = opacne(akt);
    }
    //printf("[index=%d z %d] ... ", index, radek.length() - 1);
    if(index >= 0) {
        radek[index] = opacne(radek[index]);


        index = 0;
        while(index < radek.length() && radek[index] == '0') {
            index++;
        }
        if(index == radek.length()) {
            printf("0");
        }
        else {
            for(int i=index; i<radek.length(); i++) {
                putchar(radek[i]);
            }
        }
        printf("\n");
    }
    else { // index < 0

        //printf("(%c)", akt);

        if(radek.length()%2 == 1) {
            printf("11");
        }
        else {
            printf("1");
        }

        cout << radek << endl;
    }

}

int main()
{
    //printf("%c %c\n", opacne('0'), opacne('1'));

    /*
    char radek[1000005];
    string radecek;
    while(!getline(radecek, 1000005, stdin)) {
        printf("%s\n", radecek);
    }
    */

    /*
    string znak;
    while(scanf("%c", &znak) != EOF) {
        printf("%c", znak);
    }
    */

    string radek;
    while(cin >> radek) {
       //cout << radek << endl;
       Zpracuj(radek);
    }
    return 0;
}