// includes
#include <bits/stdc++.h>
using namespace std;

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define bit(n) (1LL<<(n))
// functions
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const ll mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(20);}
} fast_io_;


template <int MS = 2>
struct RollingHash{
  const long long mod[2] = {999999937LL, 1000000007LL};
  const long long base[2] = {9973, 10007};
  vector<long long> hash[MS], power[MS];
  int n = 0;
  RollingHash(){}
  RollingHash(const string &s){
    n = s.size();
    for(int i = 0; i < MS; i++){
      hash[i].assign(n + 1, 0);
      power[i].assign(n + 1, 0);
      hash[i][0] = 0;
      power[i][0] = 1;
      for(int j = 0; j < n; j++){
        power[i][j+1] = power[i][j] * base[i] % mod[i];
        hash[i][j+1] = (hash[i][j] * base[i] + s[j]) % mod[i];
      }
    }
  }
  long long get(int l, int r, int i) const{
    return ((hash[i][r] - hash[i][l] * power[i][r-l]) % mod[i] + mod[i]) % mod[i];
  }
  bool match(int l1, int r1, int l2, int r2) const{
    bool res = true;
    for(int i = 0; i < MS; i++){
      res &= (get(l1, r1, i) == get(l2, r2, i));
    }
    return res;
  }
  bool match(int l1, int r1, const RollingHash<MS> &rs, int l2, int r2){
    bool res = true;
    for(int i = 0; i < MS; i++){
      res &= (get(l1, r1, i) == rs.get(l2, r2, i));
    }
    return res;
  }
};

vector<int> zarray(const string &s){
  int n = s.size();
  vector<int> z(n, 0);
  int c = 0;
  for(int i = 1; i < n; i++){
    if(i + z[i - c] < c + z[c]){
      z[i] = z[i - c];
    }else{
      int j = max(0, c + z[c] - i);
      while(i + j < n && s[j] == s[i + j])j++;
      z[i] = j;
      c = i;
    }
  }
  z[0] = n;
  return z;
}

int main(int argc, char const* argv[])
{
  int n;
  cin >> n;
  string s;
  cin >> s;
  int res = 0;
  for(int i = 0; i < n; i++){
    string t = s.substr(i, sz(s) - i);
    auto v = zarray(t);
    for(int j = 0; j < sz(v); j++){
      int tmp = min(j, v[j]);
      res = max(res, tmp);
    }
  }
  cout << res << endl;
  return 0;
}


Measured memory_bytes: 384