begin
var s := ReadlnString();
if s.Length.IsOdd then
Write(s[(1 + s.Length) div 2])
else
Write(s[s.Length div 2], s[s.Length div 2 + 1])
end.
begin
var s := ReadlnString();
if s.Length.IsOdd then
Write(s[(1 + s.Length) div 2])
else
Write(s[s.Length div 2], s[s.Length div 2 + 1])
end.