#include <algorithm>
#include <iterator>
#include <iostream>
using namespace std;
int main() {
int i=0;
copy_if(
istream_iterator<char>(cin>>noskipws),
istream_iterator<char>(),
ostream_iterator<char>(cout),
[&i](const char &ch) {return (++i)%2;}
);
cout<<endl;
return 0;
}
// https://paiza.jp/poh/enshura-second/8e09c5dc