#include <algorithm>
#include <functional>
#include <iostream>
#include <iomanip>
#include <vector>
#include <map>
#include <set>
#include <unordered_set>
#include <queue>
#include <numeric>
#include <bitset>
#include <cmath>

using namespace std;
using ll = long long;
using ull = unsigned long long;
// const ll mod =  998244353 ;
const ll mod =  1000000007 ;
const ll inf = 1e18;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, 1, -1};


#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REP_FROM(i, j, n) for (ll i = (j); i < (n); ++i)
#define REP_REV(i, n) for (ll i = n-1; i >= 0; --i)
#define REP_FROM_REV(i, j, n) for (ll i = n-1; i >= j; --i)
#define all(x) (x).begin(),(x).end()
#define sz(x) ll(x.size())
template<typename T> inline T chmax(T& a, const T b) { return a = (a < b) ? b : a; }
template<typename T> inline T chmin(T& a, const T b) { return a = (a > b) ? b : a; }

ll power(ll base, ll exponent){ if(exponent % 2){ return power(base, exponent - 1) * base % mod; }else if(exponent){ ll root_ans = power(base, exponent / 2); return root_ans * root_ans % mod; }else{ return 1; }}
ll inverse(ll x){ return power(x, mod - 2);}
ll gcd(ll a, ll b) {if(a < b) gcd(b, a);ll r;while(r=a%b) {a=b;b=r;}return b;}
template<typename T> ll sum(T begin, T end) {return accumulate(begin, end, 0ll);}
struct combination{ vector<ll> fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } ll C(int p, int q) const{ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } };

using Pair = pair<ll, ll>;

template <ll Modulus> struct ModInt {
    ll a;
    constexpr ModInt(const ll x = 0) noexcept  : a((x%mod+mod) % mod){}
    constexpr ll &value() noexcept {return a;}
    constexpr const ll &value() const noexcept {return a;}
    constexpr ModInt operator+(const ModInt x) const noexcept {
      return ModInt(*this) += x;
    }
    constexpr ModInt operator-(const ModInt x) const noexcept {
      return ModInt(*this) -= x;
    }
    constexpr ModInt operator*(const ModInt x) const noexcept {
      return ModInt(*this) *= x;
    }
    constexpr ModInt operator/(const ModInt x) const noexcept {
      return ModInt(*this) /= x;
    }
    constexpr ModInt &operator+=(const ModInt x) noexcept {
      a += x.a;
      if (a >= Modulus) {
        a -= Modulus;
      }
      return *this;
    }
    constexpr ModInt &operator-=(const ModInt x) noexcept {
      if (a < x.a) {
        a += Modulus;
      }
      a -= x.a;
      return *this;
    }
    constexpr ModInt &operator*=(const ModInt x) noexcept {
      a = a * x.a % Modulus;
      return *this;
    }
    constexpr ModInt &operator/=(ModInt x) noexcept {
      ll exp = Modulus - 2;
      while (exp) {
        if (exp % 2) {
          *this *= x;
        }
        x *= x;
        exp /= 2;
      }
      return *this;
    }
    constexpr  ModInt operator-() noexcept {
      return ModInt(-a);
    }
    friend ostream& operator<<(ostream& os, const ModInt& m){
      os << m.a;
      return os;
    }
};
using mint = ModInt<mod>;


struct RollingHash {
    static const int base1 = 1007, base2 = 2009;
    static const int mod1 = 1000000007, mod2 = 1000000009;
    vector<ll> hash1, hash2, power1, power2;

    RollingHash(const string &s) {
      int n = (int)s.size();
      hash1.assign(n+1, 0);
      hash2.assign(n+1, 0);
      power1.assign(n+1, 1);
      power2.assign(n+1, 1);
      REP(i, n) {
        hash1[i+1] = (hash1[i] * base1 + s[i]) % mod1;
        hash2[i+1] = (hash2[i] * base2 + s[i]) % mod2;
        power1[i+1] = (power1[i] * base1) % mod1;
        power2[i+1] = (power2[i] * base2) % mod2;
      }
    }

    inline Pair get(int l, int r) const {
      ll res1 = hash1[r] - hash1[l] * power1[r-l] % mod1;
      if (res1 < 0) res1 += mod1;
      ll res2 = hash2[r] - hash2[l] * power2[r-l] % mod2;
      if (res2 < 0) res2 += mod2;
      return {res1, res2};
    }
};


signed main() {
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(15);
  int n;
  string s;
  cin >> n >> s;
  RollingHash rh(s);
  auto check = [&](int d) -> bool {
    map<Pair, int> m;
    REP(i, n-d+1) {
      auto p = rh.get(i, i+d);
      if(m.count(p)) {
        if(i - m[p] >= d) return true;
      }
      else{
        m[p] = i;
      }
    }
    return false;
  };

  int lft = 0;
  int rgt = n / 2 + 1;
  while(rgt - lft > 1) {
    int mid = (lft + rgt) / 2;
    if(check(mid)) {
      lft = mid;
    }
    else {
      rgt = mid;
    }
  }
  cout << lft << endl;
  return 0;
}


Measured memory_bytes: 768