object Main {
  import java.io.{BufferedReader, InputStream, InputStreamReader}
  import java.util.StringTokenizer
  import scala.reflect.ClassTag

  def main(args: Array[String]): Unit = {
    val out = new java.io.PrintWriter(System.out)
    new Main(out, new InputReader(System.in)).solve()
    out.flush()
  }

  private val oj = System.getenv("ATCODER_DEBUG") == null
  def DEBUG(f: => Unit): Unit = {
    if (!oj){ f }
  }
  def debug(as: Array[Boolean]): Unit = if (!oj){ debug(as.map(x => if(x) "1" else "0").mkString) }
  def debug(as: Array[Int]): Unit = if (!oj){ debug(as.mkString(" ")) }
  def debug(as: Array[Long]): Unit =if (!oj){ debug(as.mkString(" ")) }
  def debugDim(m: Array[Array[Long]]): Unit = if (!oj){
    REP(m.length) { i =>
      debug(m(i))
    }
  }
  def debugDimFlip(m: Array[Array[Long]]): Unit = if (!oj){
    REP(m(0).length) { j =>
      REP(m.length) { i =>
        System.err.print(m(i)(j))
        System.err.print(" ")
      }
      System.err.println()
    }
  }
  def debug(s: => String): Unit = DEBUG {
    System.err.println(s)
  }
  def debugL(num: => Long): Unit = DEBUG {
    System.err.println(num)
  }

  class InputReader(val stream: InputStream) {
    private val reader = new BufferedReader(new InputStreamReader(stream), 32768)
    private var tokenizer: StringTokenizer = _

    def next(): String = {
      while (tokenizer == null || !tokenizer.hasMoreTokens)
        tokenizer = new StringTokenizer(reader.readLine)
      tokenizer.nextToken
    }

    def nextInt(): Int = Integer.parseInt(next())
    def nextLong(): Long = java.lang.Long.parseLong(next())
    def nextChar(): Char = next().charAt(0)

    def ni(): Int = nextInt()
    def nl(): Long = nextLong()
    def nc(): Char = nextChar()
    def ns(): String = next()
    def ns(n: Int): Array[Char] = ns().toCharArray
    def na(n: Int, offset: Int = 0): Array[Int] = map(n)(_ => ni() + offset)
    def na2(n: Int, offset: Int = 0): (Array[Int], Array[Int]) = {
      val A1, A2 = Array.ofDim[Int](n)
      REP(n) { i =>
        A1(i) = ni() + offset
        A2(i) = ni() + offset
      }
      (A1, A2)
    }
    def nm(n: Int, m: Int): Array[Array[Int]] = {
      val A = Array.ofDim[Int](n, m)
      REP(n) { i =>
        REP(m) { j =>
          A(i)(j) = ni()
        }
      }
      A
    }
    def nal(n: Int): Array[Long] = map(n)(_ => nl())
    def nm_c(n: Int, m: Int): Array[Array[Char]] = map(n) (_ => ns(m))
  }

  def REP(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = offset
    val N = n + offset
    while(i < N) { f(i); i += 1 }
  }
  def REP_r(n: Int, offset: Int = 0)(f: Int => Unit): Unit = {
    var i = n - 1 + offset
    while(i >= offset) { f(i); i -= 1 }
  }
  def TO(from: Int, to: Int)(f: Int => Unit): Unit = {
    REP(to - from + 1, from) { i =>
      f(i)
    }
  }
  def map[@specialized A: ClassTag](n: Int, offset: Int = 0)(f: Int => A): Array[A] = {
    val res = Array.ofDim[A](n)
    REP(n)(i => res(i) = f(i + offset))
    res
  }

  def sumL(as: Array[Int]): Long = {
    var s = 0L
    REP(as.length)(i => s += as(i))
    s
  }
  def cumSum(as: Array[Int]): Array[Long] = {
    val cum = Array.ofDim[Long](as.length + 1)
    REP(as.length) { i =>
      cum(i + 1) = cum(i) + as(i)
    }
    cum
  }
}

class Main(out: java.io.PrintWriter, sc: Main.InputReader) {
  import sc._
  import Main._
  import java.util.Arrays.sort

  import scala.collection.mutable
  import math.{abs, max, min}
  import mutable.ArrayBuffer

  // toIntとか+7とかするならvalにしろ
  @inline private def MOD = 1000000007

  /**
    * 大文字小文字が混ざってる場合はうまくいかないので注意
    */
  def suffixArray(s: String): Array[Int] = {
    val n = s.length

    val sa = Array.iterate(0, n + 1)(_ + 1)
    val rank, tmp = Array.ofDim[Int](n + 1)
    REP(n) { i =>
      rank(i) = s(i)
    }
    rank(n) = -1

    def lt(len: Int)(i: Int, j: Int): Boolean = {
      if (rank(i) != rank(j)) rank(i) < rank(j)
      else {
        // 長さが足りないってことは文字がないてことなので、辞書順で先になる
        val ri = if (i + len <= n) rank(i + len) else -1
        val rj = if (j + len <= n) rank(j + len) else -1
        ri < rj
      }
    }

    var len = 1
    while(len <= n) {
      import scala.util.Sorting
      // 今のランクとダブリングをつかってlen*2までの長さで並び替える
      Sorting.quickSort[Int](sa)(Ordering.fromLessThan(lt(len)))

      // 次のlen*2の長さで並び替えたsaからrankの値を計算する
      tmp(sa(0)) = 0
      REP(n, 1) { i =>
        tmp(sa(i)) = tmp(sa(i - 1)) + (if (lt(len)(sa(i - 1), sa(i))) 1 else 0) // 前の順位のものより大きい場合は+1する
      }

      Array.copy(tmp, 0, rank, 0, n + 1)
      len *= 2
    }
    sa
  }

  def longestCommonPrefix(s: String, sa: Array[Int]): (Array[Int], Array[Int]) = {
    val n = s.length
    val lcp = Array.ofDim[Int](n + 1)
    val rank = Array.ofDim[Int](n + 1)
    REP(n + 1) { i =>
      rank(sa(i)) = i
    }
    var h = 0
    REP(n) { i =>
      val j = sa(rank(i) - 1) // sa上で１個前
      h = max(0, h - 1)
      while(i + h < n && j + h < n && s(i + h) == s(j + h)) {
        h += 1
      }
      lcp(rank(i)) = h
    }
    (lcp, rank)
  }

  def solve(): Unit = {
    val N = ni()
    val S = ns()
    val sa = suffixArray(S)
    val (lcp, _) = longestCommonPrefix(S, sa)
    debug(sa)
    debug(lcp)

    var ans = 0
    REP(N - 1, 1) { i =>
      var l = 1e9.toInt
      var j = i + 1
      while (j <= N) {
        l = min(l, lcp(j))
        ans = max(ans, min(l, abs(sa(j) - sa(i))))
        j += 1
      }
    }

    out.println(ans)
  }
}

Measured memory_bytes: 42604