Chef Notani and Repetition

Chef Notani had scribbled some characters on a page which created a long, continuous string. He loved finding repetitions in strings, so he decided to find out the longest non-overlapping, repeated substring in his string. In other words, he wanted to find 2 substrings in his string, which did not overlap, and were exactly the same. Help Chef Notani solve this task and print the length of the l