#include <bits/stdc++.h>
using namespace std;
/*
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
	#include <boost/multiprecision/cpp_int.hpp>
	#include <boost/multiprecision/cpp_dec_float.hpp>
	using bll = boost::multiprecision::cpp_int;
	using bdouble = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<100>>;
	using namespace boost::multiprecision;
#endif
*/
#ifdef LOCAL_TEST
	#define BOOST_STACKTRACE_USE_ADDR2LINE
	#define BOOST_STACKTRACE_ADDR2LINE_LOCATION /usr/local/opt/binutils/bin/addr2line
	#define _GNU_SOURCE 1
	#include <boost/stacktrace.hpp>
	namespace std {
		template<typename T> class dvector : public std::vector<T> {
		public:
			dvector() : std::vector<T>() {}
			explicit dvector(size_t n, const T& value = T()) : std::vector<T>(n, value) {}
			dvector(const std::vector<T>& v) : std::vector<T>(v) {}
			dvector(const std::initializer_list<T> il) : std::vector<T>(il) {}
			dvector(const std::string::iterator first, const std::string::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::iterator first, const typename std::vector<T>::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::reverse_iterator first, const typename std::vector<T>::reverse_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_iterator first, const typename std::vector<T>::const_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_reverse_iterator first, const typename std::vector<T>::const_reverse_iterator last) : std::vector<T>(first, last) {}
			T& operator[](size_t n) {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
			const T& operator[](size_t n) const {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
		};
	}
	class dbool {
	private:
		bool boolvalue;
	public:
		dbool() : boolvalue(false) {}
		dbool(bool b) : boolvalue(b) {}
		operator bool&() { return boolvalue; }
		operator const bool&() const { return boolvalue; }
	};
	#define vector dvector
	#define bool dbool
	class SIGFPE_exception : std::exception {};
	class SIGSEGV_exception : std::exception {};
	void catch_SIGFPE([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGFPE_exception(); }
	void catch_SIGSEGV([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGSEGV_exception(); }
	signed convertedmain();
	signed main() { signal(SIGFPE, catch_SIGFPE); signal(SIGSEGV, catch_SIGSEGV); return convertedmain(); }
	#define main() convertedmain()
#endif
#ifdef LOCAL_DEV
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<std::vector<T>>& vv) {
		s << "\\\n"; for (size_t i = 0; i < vv.size(); ++i){ s << vv[i] << "\n"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::deque<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::set<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::multiset<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template <typename T, size_t N> std::ostream& operator<<(std::ostream& s, const std::array<T, N>& a) {
		s << "{ "; for (size_t i = 0; i < N; ++i){ s << a[i] << "\t"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::map<T1, T2>& m) {
		s << "{\n"; for (auto itr = m.begin(); itr != m.end(); ++itr){ s << "\t" << (*itr).first << " : " << (*itr).second << "\n"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::pair<T1, T2>& p) {
		return s << "(" << p.first << ", " << p.second << ")"; }
	void debug_impl() { std::cerr << '\n'; }
	template<typename Head, typename... Tail> void debug_impl(Head head, Tail... tail) { std::cerr << " " << head << (sizeof...(tail) ? "," : ""); debug_impl(tail...); }
	#define debug(...) do { std::cerr << "(" << #__VA_ARGS__ << ") ="; debug_impl(__VA_ARGS__); } while (false)
#else
	#define debug(...) do {} while (false)
#endif
//#define int long long
using ll = long long;
//constexpr int INF = (ll)1e9 + 7;//INT_MAX=(1<<31)-1=2147483647
constexpr ll INF = (ll)1e18;//(1LL<<63)-1=9223372036854775807
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr ll dx[4] = {1, 0, -1, 0};
constexpr ll dy[4] = {0, 1, 0, -1};
constexpr ll dx8[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr ll dy8[8] = {0, 1, 0, -1, 1, -1, 1, -1};
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define rrep(i, n)   for(ll i=(n)-1; i>=0; --i)
#define rrepeq(i, n) for(ll i=(n)  ; i>=1; --i)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
void p() { std::cout << '\n'; }
template<typename Head, typename... Tail> void p(Head head, Tail... tail) { std::cout << head << (sizeof...(tail) ? " " : ""); p(tail...); }
template<typename T> inline void pv(std::vector<T>& v) { for(ll i=0, N=v.size(); i<N; i++) std::cout << v[i] << " \n"[i==N-1]; }
template<typename T> inline bool chmax(T& a, T b) { return a < b && (a = b, true); }
template<typename T> inline bool chmin(T& a, T b) { return a > b && (a = b, true); }
template<typename T> inline void uniq(std::vector<T>& v) { v.erase(std::unique(v.begin(), v.end()), v.end()); }

/*-----8<-----template-----8<-----*/

/*
RollingHash(s, mod, base):= 文字列 s のハッシュテーブルを構築する。
get(l, r):= 区間 [l,r) のハッシュ値を求める。
connect(h1, h2, h2len):= ハッシュ値 h1 と, 長さ h2len のハッシュ値 h2 を結合する。
LCP(b, l1, r1, l2, r2):= 区間 [l1,r1) と, ハッシュテーブルが b からなる区間 [l2,r2) の文字列の最長共通接頭辞の長さを求める。
*/


//using uint128_t = __uint128_t;
static constexpr __uint128_t mod = (1ull << 61ull) - 1;
__uint128_t power[1010101];
__uint128_t rhbase;
static inline uint64_t add(uint64_t a, uint64_t b) {
	if((a += b) >= mod) { a -= mod; } return a;
}
static inline uint64_t mul(uint64_t a, uint64_t b) {
	__uint128_t c = (__uint128_t) a * b; return add(c >> 61, c & mod);
}
void init_rollinghash(){
	mt19937_64 mt(chrono::steady_clock::now().time_since_epoch().count());
	uniform_int_distribution< __uint128_t > rand(1, mod - 1);
	rhbase = rand(mt);
	power[0] = 1;
	for(ll i = 0; i < 1010100; i++) {
		power[i + 1] = mul(power[i], rhbase);
	}
}
class RollingHash {
public:
	vector< __uint128_t > hashed;
	const __uint128_t base;

	/*
	static inline __uint128_t generate_base() {
		mt19937_64 mt(chrono::steady_clock::now().time_since_epoch().count());
		uniform_int_distribution< __uint128_t > rand(1, mod - 1);
		return rand(mt);
	}
	*/
	RollingHash() = default;
 
	RollingHash(const string &s, __uint128_t base = rhbase) : base(base) {
		ll sz = s.size();
		hashed.assign(sz + 1, 0);
		for(ll i = 0; i < sz; i++) {
			hashed[i + 1] = add(mul(hashed[i], base), s[i]);
		}
	}
 
	template< typename T >
	RollingHash(const vector< T > &s, __uint128_t base = rhbase) : base(base) {
		size_t sz = s.size();
		hashed.assign(sz + 1, 0);
		for(ll i = 0; i < sz; i++) {
			hashed[i + 1] = add(mul(hashed[i], base), s[i]);
		}
	}
 
	__uint128_t query(ll l, ll r) const {
		return add(hashed[r], mod - mul(hashed[l], power[r - l]));
	}
 
	__uint128_t combine(__uint128_t h1, __uint128_t h2, size_t h2len) const {
		return add(mul(h1, power[h2len]), h2);
	}
 
	ll lcp(const RollingHash &b, ll l1, ll r1, ll l2, ll r2) const {
		assert(base == b.base);
		ll len = min(r1 - l1, r2 - l2);
		ll low = 0, high = len + 1;
		while(high - low > 1) {
			ll mid = (low + high) / 2;
			if(query(l1, l1 + mid) == b.query(l2, l2 + mid)) low = mid;
			else high = mid;
		}
		return low;
	}
};

/*-----8<-----library-----8<-----*/

signed main() {
	//https://atcoder.jp/contests/abc141/tasks/abc141_e
	ll N;
	string S;
	cin>>N>>S;

	init_rollinghash();
	RollingHash rh(S);
	
	auto isOK = [&](ll len){
		map<__uint128_t, ll> m;
		for (ll i = 0; i + len <= N; ++i) {
			__uint128_t hash = rh.query(i, i+len);
			if (m.count(hash)) {
				if (i - m[hash] >= len) return true;
			} else {
				m[hash] = i;
			}
		}
		return false;
	};

	ll left = 0, right = N/2 + 1;
	while (right - left > 1) {
		ll mid = (left + right) / 2;
		if (isOK(mid)) left = mid;
		else right = mid;
	}
	
	cout<<left<<endl;
	return 0;
}


Measured memory_bytes: 19888