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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pullull;
typedef pair<ll, int> plli;
typedef pair<int, pii> pipii;
typedef vector<vector<int> > mati;
typedef vector<vector<double> > matd;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;

#define FOR(i,x,y) for(ll i=(ll)x; i<(ll)y; ++i)
#define REP(i,y) FOR(i, 0, y)
#define RFOR(i,x,y) for(ll i=(ll)x; i>=(ll)y; --i)
#define RREP(i,x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_printf(x...) cerr << "line " << __LINE__ << " : "; debug_printf_in(x);

template <typename First>
void debug_printf_in(First first){
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_printf_in(First first, Rest... rest){
  cerr << first << " ";
  debug_printf_in(rest...);
  return;
}

void IN(void){
  return;
}

template <typename First, typename... Rest>
void IN(First& first, Rest&... rest){
  cin >> first;
  IN(rest...);
  return;
}

template <typename First>
void OUT(First first){
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest){
  cout << first << " ";
  OUT(rest...);
  return;
}

template<class t, class u> void chmax(t&a,u b){if(a<b)a=b;};
template<class t, class u> void chmin(t&a,u b){if(a>b)a=b;};
int popcount(int t){return __builtin_popcount(t);} //GCC
int popcount(ll t){return __builtin_popcountll(t);} //GCC

template <typename T>
void vec_print(vector<T> VEC){
  REP(i, VEC.size()){
    cout << VEC[i] << " ";
  }
  cout << "\n";
};

template <typename T>
void mat_print(vector<vector<T> > MAT){
  REP(i, MAT.size()){
    REP(j, MAT[i].size()){
      cout << MAT[i][j] << " ";
    }
    cout << "\n";
  }
};

template <typename CLASS1, typename CLASS2>
class HOGE{
  public:
    CLASS1 key;
    CLASS2 value;
    HOGE(void){
      return;
    };
    HOGE(CLASS1 key, CLASS2 value){
      this->key = key;
      this->value = value;
    };
    ~HOGE(void){
      return;
    };

    void print(void){
      cout << "key : " << key << ", value : " << value << "\n";
      return;
    };
    
    bool operator==(const HOGE &obj){
      return (this->value == obj.value);
    };
    bool operator<(const HOGE &obj){
      return (this->value < obj.value);
    };
    bool operator>(const HOGE &obj){
      return (this->value > obj.value);
    };
};

template <typename CLASS1, typename CLASS2>
bool operator==(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value == hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator<(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value < hoge2.value;
};

template <typename CLASS1, typename CLASS2>
bool operator>(const HOGE<CLASS1, CLASS2> &hoge1, const HOGE<CLASS1, CLASS2> &hoge2){
  return hoge1.value > hoge2.value;
};

constexpr int INF = (1<<30);
constexpr ll INFLL = 1LL<<62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9)+7);

class Z_algorithm{
  private:
    string S;
    vll A;
    vb B;

  public:
    Z_algorithm(string s){
      S = s;
      A.resize(S.size());
      B.resize(S.size());
      return;
    };

    ~Z_algorithm(void){
      return;
    };

    void calc(string S, vll& A){
      A[0] = S.size();
      ll i=1, j=0;
      while(i<S.size()){
        while(i+j < S.size() && S[j] == S[i+j]) ++j;
        A[i] = j;
        if(j==0){
          ++i;
          continue;
        }
        ll k=1;
        while(i+k<S.size() && k+A[k]<j){
          A[i+k] = A[k];
          ++k;
        }
        i += k;
        j -= k;
      }
      return;
    };

    void calc(void){
      calc(S, A);
      return;
    }

    ll calc_check(ll pos){
      return A[pos];
    };

    void find(string W){
      vll A_buf(S.size() + W.size());
      calc(W+S, A_buf);
      for(ll i=0; i<S.size(); ++i){
        if(A_buf[W.size() + i] >= W.size()) B[i] = true;
        else                                B[i] = false;
      }
      return;
    };

    bool find_check(ll pos){
      return B[pos];
    };
};

int main(){
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after std::cin)
  ios::sync_with_stdio(false); // cut the iostream and stdio (DON'T endl; BUT "\n";)

  string S;
  ll N;
  IN(N);
  IN(S);
  string s = "";
  ll n = s.size();
  ll ans = 0;
  RREP(i,N-1){
    s = S[i]+s;
    n = s.size();
    //debug_printf(i, s);
    Z_algorithm ZA(s);
    ZA.calc();
    REP(j,n){
      //debug_printf(j, ZA.calc_check(j));
      ans = max(ans, min(min(j, n-j), ZA.calc_check(j)));
    }
  }

  OUT(ans);

  return 0;
}


Measured memory_bytes: 384