import std.stdio, std.string, std.range, std.algorithm;

void main() {
    string s = strip(readln());
    size_t n = s.length;
    auto odd = filter!(a => a%2 == 0)(iota(n));
    foreach (c; map!(i => s[i])(odd)) {
        write(c);
    }
    writeln();
}

