> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/l/longest_string_challenge.md).

# Longest string challenge

```ruby
var l = ''  # Sample longest string seen.
var a = ''  # Accumulator to save longest strings.
 
STDIN.each { |n|
    n.substr(l.len) ? (a = n; l = n)
                    : (!l.substr(n.len) && a.concat!(n))
}
 
print a
```