#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

#define NDEBUG
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<typename T> constexpr T popcount(const T u) { return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T log2p1(const T u) { return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template<typename T> constexpr T lsbp1(const T u) { return __builtin_ffsll(u); }
template<typename T> constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast<T>(u); }
template<typename T> constexpr bool ispow2(const T u) { return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0; }
template<typename T> constexpr T ceil2(const T u) { return static_cast<T>(1) << clog(u); }
template<typename T> constexpr T floor2(const T u) { return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1); }
template<typename T> constexpr bool btest(const T mask, const usize ind) { return ((static_cast<u64>(mask) >> ind) & static_cast<u64>(1)); }
template<typename T> constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast<T>(0) : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >> (64 - ind)); }
template<typename T> bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template<typename T> bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
constexpr unsigned int mod                  = 1000000007;
template<typename T> constexpr T inf_v      = std::numeric_limits<T>::max() / 4;
template<typename Real> constexpr Real pi_v = Real{3.141592653589793238462643383279502884};


/**
 * http://xoshiro.di.unimi.it/xoshiro128starstar.c
 * http://xoshiro.di.unimi.it/xoshiro256starstar.c
 * http://xoshiro.di.unimi.it/splitmix64.c
 */
class xoshiro
{
public:
    using result_type = uint32_t;
    static constexpr result_type min() { return std::numeric_limits<result_type>::min(); }
    static constexpr result_type max() { return std::numeric_limits<result_type>::max(); }
    xoshiro() : xoshiro(std::random_device{}()) {}
    xoshiro(uint64_t seed)
    {
        uint64_t z = 0;
        for (int i = 0; i < 4; i++) { z = (seed += 0x9e3779b97f4a7c15), z = (z ^ (z >> 33)) * 0x62A9D9ED799705F5, z = (z ^ (z >> 28)) * 0xCB24D0A5C88C35B3, s[i] = static_cast<result_type>(z >> 32); }
    }
    result_type operator()()
    {
        const result_type result = rotl(s[1] * 5, 7) * 9, t = s[1] << 9;
        return s[2] ^= s[0], s[3] ^= s[1], s[1] ^= s[2], s[0] ^= s[3], s[2] ^= t, s[3] = rotl(s[3], 11), result;
    }
    void discard(const usize rep)
    {
        for (usize i = 0; i < rep; i++) { (*this)(); }
    }

private:
    result_type s[4];
    static result_type rotl(const result_type x, const int k) { return (x << k) | (x >> (32 - k)); }
};
class xoshiro_64
{
public:
    using result_type = uint64_t;
    static constexpr result_type min() { return std::numeric_limits<result_type>::min(); }
    static constexpr result_type max() { return std::numeric_limits<result_type>::max(); }
    xoshiro_64() : xoshiro_64(std::random_device{}()) {}
    xoshiro_64(uint64_t seed)
    {
        uint64_t z = 0;
        for (int i = 0; i < 4; i++) { z = (seed += 0x9e3779b97f4a7c15), z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9, z = (z ^ (z >> 27)) * 0x94d049bb133111eb, s[i] = static_cast<result_type>(z ^ (z >> 31)); }
    }
    result_type operator()()
    {
        const result_type result = rotl(s[1] * 5, 7) * 9, t = s[1] << 17;
        return s[2] ^= s[0], s[3] ^= s[1], s[1] ^= s[2], s[0] ^= s[3], s[2] ^= t, s[3] = rotl(s[3], 45), result;
    }
    void discard(const usize rep)
    {
        for (usize i = 0; i < rep; i++) { (*this)(); }
    }

private:
    result_type s[4];
    static result_type rotl(const result_type x, const int k) { return (x << k) | (x >> (64 - k)); }
};
template<typename Rng>
class rng_base
{
public:
    using rng_type    = Rng;
    using result_type = typename rng_type::result_type;
    static constexpr result_type min() { return rng_type::min(); }
    static constexpr result_type max() { return rng_type::max(); }
    rng_base() : rng_base(std::random_device{}()) {}
    rng_base(const u64 seed) : rng(seed) {}
    ~rng_base() = default;
    result_type operator()() { return rng(); }
    template<typename Int>
    Int uniform_int(const Int max)
    {
        static_assert(std::is_integral<Int>::value, "Integer type is needed.");
        if (ispow2(max + 1)) { return static_cast<Int>(rng() & max); }
        const result_type mask = static_cast<result_type>(ceil2(static_cast<u64>(max + 1))) - 1;
        while (true) {
            const Int ans = static_cast<Int>(rng() & mask);
            if (ans <= max) { return ans; }
        }
    }
    template<typename Int> Int uniform_int(const Int min, const Int max) { return min + uniform_int(static_cast<Int>(max - min)); }
    bool uniform_bool() { return uniform_int<bool>(0, 1); }
    template<typename Real>
    Real uniform_real()
    {
        static_assert(std::is_floating_point<Real>::value, "FloatingPoint type is needed.");
        return static_cast<Real>(uniformInt(~static_cast<result_type>(0)) / static_cast<Real>(~static_cast<result_type>(0)));
    }
    template<typename Real> Real uniform_real(const Real min, const Real max) { return assert(min <= max), uniform_real<Real>() * (max - min) + min; }
    template<typename Int> std::pair<Int, Int> uniform_int_pair(const Int min, const Int max) { return std::minmax(uniform_int(min, max), uniform_int(min, max)); }
    template<typename Int>
    std::vector<Int> uniform_int_vec(const std::size_t size, const Int min, const Int max)
    {
        std::vector<Int> v(size);
        for (std::size_t i = 0; i < size; i++) { v[i] = uniformInt(min, max); }
        return v;
    }
    template<typename Real>
    std::vector<Real> uniform_real_vec(const std::size_t size, const Real min, const Real max)
    {
        std::vector<Real> v(size);
        for (std::size_t i = 0; i < size; i++) { v[i] = uniformReal(min, max); }
        return v;
    }
    void discard(const usize rep) { rng.discard(rep); }

private:
    Rng rng;
};
using rng_mt        = rng_base<std::mt19937>;
using rng_mt64      = rng_base<std::mt19937_64>;
using rng_xoshiro   = rng_base<xoshiro>;
using rng_xoshiro64 = rng_base<xoshiro_64>;
rng_mt g_rng_mt;
rng_mt64 g_rng_mt64;
rng_xoshiro g_rng_xo;
rng_xoshiro64 g_rng_xo64;
template<typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template<typename T>
std::vector<T> read_vec(const std::size_t size)
{
    std::vector<T> v(size);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
#define SHOW(...) static_cast<void>(0)
template<typename T>
std::vector<T> make_v(const std::size_t size, T v) { return std::vector<T>(size, v); }
template<class... Args>
auto make_v(const std::size_t size, Args... args) { return std::vector<decltype(make_v(args...))>(size, make_v(args...)); }



template<typename T> T gcd(const T& a, const T& b) { return (a > b ? gcd(b, a) : a == 0 ? b : gcd(b % a, a)); }
template<typename T> T lcm(const T& a, const T& b) { return a / gcd(a, b) * b; }
template<typename T>
constexpr std::pair<T, T> extgcd(const T a, const T b)
{
    if (b == 0) { return std::pair<T, T>{1, 0}; }
    const auto g = gcd(a, b), da = std::abs(b) / g;
    const auto p = extgcd(b, a % b);
    const auto x = (da + p.second % da) % da, y = (g - a * x) / b;
    return {x, y};
}
template<typename T>
constexpr T inverse(const T a, const T mod) { return extgcd(a, mod).first; }
template<uint mod_value, bool dynamic = false>
class modint_base
{
public:
    template<typename UInt = uint>
    static std::enable_if_t<dynamic, const UInt> mod() { return mod_ref(); }
    template<typename UInt = uint>
    static constexpr std::enable_if_t<not dynamic, const UInt> mod() { return mod_value; }
    template<typename UInt = uint>
    static void set_mod(const std::enable_if_t<dynamic, const UInt> mod) { mod_ref() = mod; }
    modint_base() : v{0} {}
    modint_base(const ll val) : v{norm(static_cast<uint>(val % static_cast<ll>(mod()) + static_cast<ll>(mod())))} {}
    modint_base(const modint_base& n) : v{n()} {}
    explicit operator bool() const { return v != 0; }
    bool operator!() const { return not static_cast<bool>(*this); }
    modint_base& operator=(const modint_base& m) { return v = m(), (*this); }
    modint_base& operator=(const ll val) { return v = norm(uint(val % static_cast<ll>(mod()) + static_cast<ll>(mod()))), (*this); }
    friend modint_base operator+(const modint_base& m) { return m; }
    friend modint_base operator-(const modint_base& m) { return make(norm(mod() - m.v)); }
    friend modint_base operator+(const modint_base& m1, const modint_base& m2) { return make(norm(m1.v + m2.v)); }
    friend modint_base operator-(const modint_base& m1, const modint_base& m2) { return make(norm(m1.v + mod() - m2.v)); }
    friend modint_base operator*(const modint_base& m1, const modint_base& m2) { return make(static_cast<uint>(static_cast<ll>(m1.v) * static_cast<ll>(m2.v) % static_cast<ll>(mod()))); }
    friend modint_base operator/(const modint_base& m1, const modint_base& m2) { return m1 * inv(m2.v); }
    friend modint_base operator+(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) + val}; }
    friend modint_base operator-(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) - val}; }
    friend modint_base operator*(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) * (val % static_cast<ll>(mod()))}; }
    friend modint_base operator/(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) * inv(val)}; }
    friend modint_base operator+(const ll val, const modint_base& m) { return modint_base{static_cast<ll>(m.v) + val}; }
    friend modint_base operator-(const ll val, const modint_base& m) { return modint_base{-static_cast<ll>(m.v) + val}; }
    friend modint_base operator*(const ll val, const modint_base& m) { return modint_base{static_cast<ll>(m.v) * (val % static_cast<ll>(mod()))}; }
    friend modint_base operator/(const ll val, const modint_base& m) { return modint_base{val * inv(static_cast<ll>(m.v))}; }
    friend modint_base& operator+=(modint_base& m1, const modint_base& m2) { return m1 = m1 + m2; }
    friend modint_base& operator-=(modint_base& m1, const modint_base& m2) { return m1 = m1 - m2; }
    friend modint_base& operator*=(modint_base& m1, const modint_base& m2) { return m1 = m1 * m2; }
    friend modint_base& operator/=(modint_base& m1, const modint_base& m2) { return m1 = m1 / m2; }
    friend modint_base& operator+=(modint_base& m, const ll val) { return m = m + val; }
    friend modint_base& operator-=(modint_base& m, const ll val) { return m = m - val; }
    friend modint_base& operator*=(modint_base& m, const ll val) { return m = m * val; }
    friend modint_base& operator/=(modint_base& m, const ll val) { return m = m / val; }
    friend modint_base operator^(const modint_base& m, const ll n) { return power(m.v, n); }
    friend modint_base& operator^=(modint_base& m, const ll n) { return m = m ^ n; }
    friend bool operator==(const modint_base& m1, const modint_base& m2) { return m1.v == m2.v; }
    friend bool operator!=(const modint_base& m1, const modint_base& m2) { return not(m1 == m2); }
    friend bool operator==(const modint_base& m, const ll val) { return m.v == norm(static_cast<uint>(static_cast<ll>(mod()) + val % static_cast<ll>(mod()))); }
    friend bool operator!=(const modint_base& m, const ll val) { return not(m == val); }
    friend bool operator==(const ll val, const modint_base& m) { return m.v == norm(static_cast<uint>(static_cast<ll>(mod()) + val % static_cast<ll>(mod()))); }
    friend bool operator!=(const ll val, const modint_base& m) { return not(m == val); }
    friend std::istream& operator>>(std::istream& is, modint_base& m)
    {
        ll v;
        return is >> v, m = v, is;
    }
    friend std::ostream& operator<<(std::ostream& os, const modint_base& m) { return os << m(); }
    uint operator()() const { return v; }

private:
    template<typename UInt = uint>
    static std::enable_if_t<dynamic, UInt&> mod_ref()
    {
        static UInt mod = 0;
        return mod;
    }
    static uint norm(const uint x) { return x < mod() ? x : x - mod(); }
    static modint_base make(const uint x)
    {
        modint_base m;
        return m.v = x, m;
    }
    static modint_base power(modint_base x, ull n)
    {
        modint_base ans = 1;
        for (; n; n >>= 1, x *= x) {
            if (n & 1) { ans *= x; }
        }
        return ans;
    }
    static modint_base inv(const modint_base& x) { return modint_base{inverse(static_cast<ll>(x.v), static_cast<ll>(mod()))}; }

    uint v;
};
template<uint mod>
using modint = modint_base<mod, false>;
template<uint id>
using dynamic_modint = modint_base<id, true>;
template<uint mod>
class rolling_hash
{
public:
    template<typename InIt>
    rolling_hash(const InIt first, const InIt last) : sz(std::distance(first, last)), pow(sz + 1, 1), h(sz + 1, 0)
    {
        const ull base = g_rng_mt64.uniform_int(static_cast<uint>(2), mod - 1);
        for (usize i = 1; i <= sz; i++) { pow[i] = pow[i - 1] * base, h[i] = h[i - 1] * base + *std::next(first, i - 1); }
    }
    modint<mod> operator()(const usize l, const usize r) const { return h[r] - h[l] * pow[r - l]; }

private:
    const usize sz;
    std::vector<modint<mod>> pow, h;
};

template<usize lg>
class wavelet_matrix
{
public:
    using bucket_type                  = u64;
    static constexpr usize bucket_size = sizeof(bucket_type) * 8;
    template<typename InIt>
    wavelet_matrix(const InIt first, const InIt last) : sz{static_cast<usize>(std::distance(first, last))}
    {
        std::vector<bool> b(sz);
        std::vector<bucket_type> v{first, last};
        for (usize d = 0; d < lg; d++) {
            std::vector<bucket_type> z, o;
            for (usize i = 0; i < sz; i++) { b[i] = btest(v[i], lg - d - 1), (b[i] ? o : z).push_back(v[i]); }
            table.push_back(fid{b}), zero.push_back(z.size());
            for (usize i = 0; i < z.size(); i++) { v[i] = z[i]; }
            for (usize i = 0; i < o.size(); i++) { v[z.size() + i] = o[i]; }
        }
    }
    usize less_than(usize l, usize r, const bucket_type v) const
    {
        usize ans = 0;
        for (usize i = 0; i < lg; i++) {
            if (btest(v, lg - i - 1)) {
                ans += table[i].zero(r) - table[i].zero(l), l = zero[i] + table[i].one(l), r = zero[i] + table[i].one(r);
            } else {
                l = table[i].zero(l), r = table[i].zero(r);
            }
        }
        return ans;
    }
    usize range_freq(const usize l, const usize r, const bucket_type vmin, const bucket_type vsup) const { return less_than(l, r, vsup) - less_than(l, r, vmin); }

private:
    class fid
    {
    private:
        const usize sz;
        std::vector<bucket_type> data;
        std::vector<usize> large;

    public:
        fid(const std::vector<bool>& b) : sz(b.size()), data(sz / bucket_size + 2, 0), large(sz / bucket_size + 2, 0)
        {
            for (usize i = 0; i < sz; i++) { data[i / bucket_size] |= (static_cast<bucket_type>(b[i]) << (i % bucket_size)), large[i / bucket_size + 1] += b[i]; }
            for (usize i = 1; i < large.size(); i++) { large[i] += large[i - 1]; }
        }
        bool operator[](const usize n) const { return btest(data[n / bucket_size], n % bucket_size); }
        usize one(const usize n) const { return large[n / bucket_size] + popcount(bcut(data[n / bucket_size], n % bucket_size)); }
        usize zero(const usize n) const { return n - one(n); }
    };
    const usize sz;
    std::vector<usize> zero;
    std::vector<fid> table;
};
int main()
{
    const auto n = read<int>();
    const auto s = read<std::string>();
    rolling_hash<mod> hash(s.begin(), s.end());
    int inf = 0, sup = n / 2 + 1;
    auto ok = [&](const int mid) {
        std::vector<uint> h(n - mid + 1);
        for (int i = 0; i <= n - mid; i++) { h[i] = hash(i, i + mid)(); }
        wavelet_matrix<32> wm(h.begin(), h.end());
        for (int i = mid; i <= n - mid; i++) {
            if (wm.range_freq(0, i - mid + 1, h[i], h[i] + 1) > 0) { return true; }
        }
        return false;
    };
    while (sup - inf > 1) {
        const int mid         = (inf + sup) / 2;
        (ok(mid) ? inf : sup) = mid;
    }
    std::cout << inf << std::endl;
    return 0;
}


Measured memory_bytes: 568