/*
vrrtll==???>;::::~~~~~~......`.`````````````````````...-?777!_.._?7u,~~~::::;>>??=lllttrrzu
rtll==??>>;::::~~~~......`.`````````````````` ..J77!`````````...`..._T,~~~~:::;;>??==lttrrv
tll=??>>;:::~~~~......``````````````````..J7^ ` ``  ` `` .,```````...._4,.~~~::;;>>?===lttr
l=???>;;::~~~......`````HTSu,.``  `..J7!    `      `` .J"~N```````````..?&.~~~~::;;>>?==llt
=??>;;::~~~~.....``````.@????7SJ.?=     `     ` `` .J=....J;  ``````````..h..~~~~::;;>??=ll
?>>;::~~~~.....````````.D?>>?>?>?8+.``         `.J"_......_b`     ````````.S_.~~~~::;;>??=l
>;;::~~~~....``````````.C>??>>>?>>>?8J.`  ```..Y~..........J;  `  ` ``````` G...~~~~::;>??=
;;::~~~....```````` `..W1>>?>>>>?>>>>>?S,.`.7^.............-N``  `   ``````` 6...~~~~::;>??
;:~~~~....``````` ..7` d??>>?>?>>?>>?>>1udMgggNNNNggJ.......([          `````.L...~~~~::;>?
:~~~.....`````` .7`   `K>?>?>>>>>>+ugNMMMB""7<!~~<?7TWMNNa,..w.`  ` `  ` `````,)....~~:::;>
~~~....``````.J^     ` #>>?>>>?jgMMM9=_................-?TMMa,b` `   `  `  ````(,...~~~~:;;
~~~....``` .7``   `    @?>>?1uMM#=.........................(TMNa......  ` ``````4....~~~::;
~~~...`` .=`` `     ` .b>>jgNH".................`.............?HNmx??17TYY9SA+(..L....~~~::
~....` ,^``     `   ` .b+dN#^............6..-(,-...`............(HMm+>>>>>?>>????zOM_.~~~::
.... .=```  `` `   ...JNMM^..........`..._n.(MMN,....`..`.........?MNe<>>?>??>????d^...~~~:
~...v```` ` ..-Z""!_..(M@_........`........?7MMMMp.................-TNN+?>>>????1d4-..-(Jk9
..(^`...zY"!_........(MD..............`......JMMMMp....`..`..`......./MNx>??>>?1d!.h7=~(??=
(v_`,R_.............(NF..(/..(&,...`..........?MMMM;..................(MMs>>?1&T"!``....(1=
t..`` 4,...........(N@....?,(NMNR_.....`..`....(WMM$..`....`..`..`....._HMe7=```````....~_1
...````.4,........-dM:.....(7MMMNR-.....................`............(.?^ ``  ``````....~~~
...``````,4,....`.(NF........(MMMMb..`....--................`....(.7!        `  ````....~~:
..````` ` `.5J_...JMt.........?NMMM[...`.HH5._(J7[...`...`...--?^`          ` `````....~~~:
...````` `  ` 7a,.dM{....`...../MMMN......(J=`  .>......._(/=             `  ` `````...~~~:
....```` ``     (4MN{..........._7"^...(/^    `.C....-(J=`                  ` ` ```....~~~:
....````` `      JdM[...`...`........`_3..  ..?!..(-7!                  ` ` ``````....~~~::
r...``````  ` ``(CJMb..............`......__..-(?^                     `  `  `````....~~::;
J/...````` `  `,3>+MN-.`..`...`..........._(J=``                     `  ` ```````....~~~::;
_j,..`.```` ``.5>>?dNb...`......`......_-?'`                            `  `````....~~~::;;
~~j,..```````.D??>>>MM/....`........(-=`                          `  ` ` ```````...~~~:::;>
~~~j,...````.E??>??>?MN-.........(J=                            `   ` ` ``````....~~~~::;??
:~~~?,...``.@>?>?>>??dMN_....-(?^                        `  `    ` `  ````````...~~~~:;;>??
::~~~?/....K??????>>?>dMN-_(7!                               `  ` ` ````````....~~~:::>>??l
;:::~~/e.(K==?????????<dM"!                          `    `   ` ` `` ``````...~~~~:::;>??=l
*/
#include "bits/stdc++.h"
using namespace std;
#define ok1 printf("ok1\n")
#define ok2 printf("ok2\n")
#define M 1000000000000000000LL
#define rep(i,n) for(int i=0;i<n;++i)
#define REP(i,s,n) for(int i=(s);i<(n);++i)
#define repr(i,n) for(int i=n-1;i>=0;--i)
#define REPR(i,s,n) for(int i=(s);i>=(n);--(i))
#define all(a) (a).begin(),(a).end()
#define reall(a) (a).rbegin(),(a).rend()
#define pb emplace_back //emplace_backの方が速いが使い慣れてないため
#define DOUBLE fixed << setprecision(15)
#define fi first
#define se second
#define mp make_pair
#define mt make_tuple
#define BIT(n,m)(((n)>>(m))&1)
const double pi = acos(-1.0);
typedef vector<int> vi;
typedef vector<string> vs;
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef vector<char> vc;
typedef vector<double> vd;
typedef vector<bool> vb;
typedef deque<ll> dll;
typedef pair<ll, ll> P;
typedef vector<P> vP;
const ll mod = 1e9 + 7;
//const ll mod = 998244353;
ll dy[4] = { 1,0,-1,0 };
ll dx[4] = { 0,1,0,-1 };
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template< typename T >
struct edge {
	int src, to;
	T cost;

	edge(int to, T cost) : src(-1), to(to), cost(cost) {}

	edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

	edge &operator=(const int &x) {
		to = x;
		return *this;
	}

	operator int() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WeightedGraph = vector< Edges< T > >;
using UnWeightedGraph = vector< vector< int > >;
template< typename T >
using Matrix = vector< vector< T > >;
bool out_check(ll a, ll b) { return (0 <= a && a < b); }
void addmod(ll &a, ll &b) { a = (a + b) % mod; }
void Pvi(vi v) {
	puts("vll------------------------------------------------");
	rep(i, v.size()) cout << v[i] << " "; puts("");
	puts("------------------------------------------------");
}
void Pvll(vll v) {
	puts("vll------------------------------------------------");
	rep(i, v.size()) cout << v[i] << " "; puts("");
	puts("------------------------------------------------");
}
void Pvvll(vvll v) {
	puts("vvll------------------------------------------------");
	rep(i, v.size()) { rep(j, v[i].size()) cout << v[i][j] << " "; cout << endl; }
	puts("------------------------------------------------");
}
void Pvs(vs s) {
	puts("vs------------------------------------------------");
	rep(i, s.size()) { rep(j, s[i].size()) cout << s[i][j] << " "; cout << endl; }
	puts("------------------------------------------------");
}

void Yes(bool x) { cout << ((x) ? "Yes\n" : "No\n"); }
void YES(bool x) { cout << ((x) ? "YES\n" : "NO\n"); }
void yes(bool x) { cout << ((x) ? "yes\n" : "no\n"); }
void Yay(bool x) { cout << ((x) ? "Yay!\n" : ":(\n"); }

ll  n, m, d, e, r, l, k, h, ans, ret = M;
bool flag = false, flag2 = false, flag3 = false;
string s, t, u;

//最長共通部分文字列の探索
vector<long long> Z_algorithm(const string &s) {
	int N = s.size();
	vector<long long> a(N);
	a[0] = N;
	int i = 1, j = 0;
	while (i < N) {
		while (i + j < N&&s[j] == s[i + j])++j;
		a[i] = j;
		if (j == 0) { ++i; continue; }
		int k = 1;
		while (i + k < N&&k + a[k] < j)a[i + k] = a[k], ++k;
		i += k; j -= k;
	}
	return a;
}

int main() {
	cin.tie(0); ios::sync_with_stdio(false);//not intractive
	cin >> n>> s;
	rep(i, n) {
		ll len = n - i;
		auto v = Z_algorithm(s);
		//Pvll(v);
		rep(j, len) {
			ll num = min(v[j], (ll)j);
			ans = max(ans, num);
		}
		s.erase(s.begin());
	}
	cout << ans << endl;
	return 0;
}

Measured memory_bytes: 764