#include <iostream>
#include <array>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <algorithm>
#include <string>
#include <climits>
#include <cassert>
#include <iomanip>
#include <bitset>
#include <queue>
#include <deque>
#include <stack>
#include <functional>
#include <fstream>
#include <cmath>
#include <random>

#define LEN(x) int(x.size())
#define FOR(i,a,n) for(int i=(a);i<(n); ++i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define IS_BIT_ON(bit, i) (bit & (1 << i))
#define BIT_ON(bit, i) (bit |= (1 << i))
#define BIT_OFF(bit, i) (bit &= ~(1 << i))
#define BIT_COUNT(bit) (__builtin_popcount(bit))

typedef long long LL;
template<typename T> std::vector<T> make_v(size_t a){return std::vector<T>(a);}
template<typename T,typename... Ts> auto make_v(size_t a, Ts... ts){ return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));}    // C++14
template<typename T,typename V> typename std::enable_if<std::is_class<T>::value==0>::type fill_v(T &t,const V &v){t=v;}
template<typename T,typename V> typename std::enable_if<std::is_class<T>::value!=0>::type fill_v(T &t,const V &v){for(auto &e:t) fill_v(e,v);}
template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
void print() { std::cout << std::endl; }
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) { std::cout << head; if (sizeof...(tail) != 0) {std::cout << " ";} print(std::forward<Tail>(tail)...); }
template <class T> void print(std::vector<T> &v) {for (auto& a : v) { std::cout << a; if (&a != &v.back()) {std::cout << " ";} }std::cout << std::endl;}
template <class T> void print(std::vector<std::vector<T>> &vv) { for (auto& v : vv) { print(v); }}
void debug() { std::cerr << std::endl; }
template <class Head, class... Tail> void debug(Head&& head, Tail&&... tail) { std::cerr << head; if (sizeof...(tail) != 0) {std::cerr << " ";} print(std::forward<Tail>(tail)...); }
template <class T> void debug(std::vector<T> &v) {for (auto& a : v) { std::cerr << a; if (&a != &v.back()) {std::cerr << " ";} }std::cerr << std::endl;}
template <class T> void debug(std::vector<std::vector<T>> &vv) { for (auto& v : vv) { print(v); }}
inline bool inside(long long y, long long x, long long H, long long W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }
template<typename T> T &chmin(T &a, const T &b) { return a = std::min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = std::max(a, b); }

template<class T> inline std::vector<T> unique(std::vector<T> v) {
    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
    return v;
}

long long sum_of_arithmetic_progression(long long s, long long d, long long n) {
    return n * (2 * s + (n - 1) * d) / 2;
}

bool is_power_of_two(long long x) {
    return !(x & (x - 1));
}

long long gcd(long long a, long long b) {
    if (b == 0) { return a; }
    return gcd(b, a % b);
}

long long gcd(std::vector<long long> &v) {
    long long ans = v[0];
    for (int i = 1; i < (int)v.size(); ++i) {
        ans = gcd(ans, v[i]);
    }
    return ans;
}

long long lcm(long long a, long long b) {
    long long g = gcd(a, b);
    return a / g * b;
}

const int INF = 1u << 30u;  // 1,073,741,824
const long long LINF = 1ull << 58u;
const double EPS = 1e-9;
const long double PI = acos(-1.0);
const std::vector<int> dy2 = {0, 1}, dx2 = {1, 0};
const std::vector<int> dy4 = {0, 1, 0, -1}, dx4 = {1, 0, -1, 0};
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

template <typename T> class SegmentTree {
    const int array_size;        // もとの配列のサイズ
    int n;
    std::vector<T> data;
    std::function<T (T,T)> op;
    T unit;

public:
    enum Mode {
        RangeMinimumQuery,
        RangeMaximumQuery,
        RangeSummationQuery,
    };

    SegmentTree(int array_size, Mode mode) : array_size(array_size) {
        if (mode == RangeMinimumQuery) {
            unit = INT_MAX;
            op = [](T a, T b) { return std::min(a, b); };
        }
        else if (mode == RangeMaximumQuery) {
            unit = 0;
            op = [](T a, T b) { return std::max(a, b); };
        }
        else if (mode == RangeSummationQuery) {
            unit = 0;
            op = [](T a, T b) { return a + b; };
        }
        else {
            assert(false);
        }

        n = 1;
        while (n < array_size) { n *= 2; }   // _n以上の最小の2冪
        data.resize(2 * n - 1, unit);
    }

    template <typename F> SegmentTree(int array_size, T unit, F op) : array_size(array_size), unit(unit), op(op) {
        while (n < array_size) { n *= 2; }   // _n以上の最小の2冪
        data.resize(2 * n - 1, unit);
    }

    T access(int idx) {
        return data[idx + n - 1];
    }

    // array[idx] = x
    // O(log N)
    void update(int idx, T x) {
        assert(0 <= idx and idx < array_size);
        idx += n - 1;   // 木での対象のインデックス
        data[idx] = x;
        while (idx > 0) {
            idx = (idx - 1) / 2;                                    // 親のインデックス
            data[idx] = op(data[idx * 2 + 1], data[idx * 2 + 2]);   // 左の子と右の子
        }
    }

    // op(array[left, right))
    // O(log N)
    T query(int left, int right) const {
        assert(0 <= left and left < right and right <= array_size);
        return query(left, right, 0, 0, n);
    }

private:
    // [a, b)の目的値をノードk（区間[l, r]）から検索
    T query(int a, int b, int k, int l, int r) const {
        assert(a < b && l < r);
        // 範囲外
        if (r <= a || b <= l) {
            return unit;
        }
        // 完全に含む
        if (a <= l && r <= b) {
            return this->data[k];
        }
            // 一部含む
        else {
            T vl = query(a, b, k * 2 + 1, l, (l + r) / 2);    // 左の子
            T vr = query(a, b, k * 2 + 2, (l + r) / 2, r);    // 右の子
            return op(vl, vr);
        }
    }
};


class SuffixArray {
private:
    int n, k;
    std::vector<int> rank;
    SegmentTree<int> st_mini;
    SegmentTree<int> st_maxi;

public:
    const std::string s;
    std::vector<int> sa;
    std::vector<int> lcp;

public:
    SuffixArray(const std::string &s) : n(s.size()), s(s),
                                        st_mini(s.size() + 1, SegmentTree<int>::RangeMinimumQuery),
                                        st_maxi(s.size() + 1, SegmentTree<int>::RangeMaximumQuery) {
        sa.assign(n + 1, 0);
        lcp.assign(n + 1, 0);
        rank.assign(n + 1, 0);
    }

    void build() {
        this->construct_sa();
        this->construct_lcp();

        for (int i = 0; i < sa.size(); ++i) {
            st_mini.update(i, sa[i]);
            st_maxi.update(i, sa[i]);
        }

    }

    // sの(left, right)がpatternを含んでいるか
    // O(|pattern| log |S|)
    bool contain(const string &pattern) const {
        const int pattern_size = pattern.size();

        int left = -1;
        int right = n;
        while (right - left > 1) {
            int c = (left + right) / 2;
            // Sのsa[c]文字目から|pattern|文字をpatternを比較
            if (s.compare(sa[c], pattern_size, pattern) < 0) {
                left = c;
            }
            else {
                right = c;
            }
        }

        return s.compare(sa[right], pattern_size, pattern) == 0;
    }

    // s上で最初にpatternが出現する位置(0-index)
    int find_first(const string &pattern) const {
        const auto l = this->lower_bound_sa(pattern);
        const auto u = this->upper_bound_sa(pattern);
        if (l == -1 or u == -1) {
            return -1;
        }
        return this->st_mini.query(l, u + 1);
    }

    // s上で最後にpatternが出現する位置(0-index)
    int find_last(const string &pattern) const {
        const auto l = this->lower_bound_sa(pattern);
        const auto u = this->upper_bound_sa(pattern);
        if (l == -1 or u == -1) {
            return -1;
        }
        return this->st_maxi.query(l, u + 1);
    }

    // sa上で最後にpatternが現れる位置
    int lower_bound_sa(const string &pattern) const {
        const int pattern_size = pattern.size();

        int left = -1, right = n;
        while (right - left > 1) {
            int c = (left + right) / 2;
            int ret = s.compare(sa[c], pattern_size, pattern);
            // patternが大きい
            if (ret >= 0) {
                right = c;
            }
            else {
                left = c;
            }
        }
        if (s.compare(sa[right], pattern_size, pattern) == 0) {
            return right;
        }
        return -1;
    }

    // sa上で最初にpatternが現れる位置
    int upper_bound_sa(const string &pattern) const {
        const int pattern_size = pattern.size();

        int left = -1, right = n + 1;
        while (right - left > 1) {
            int c = (left + right) / 2;
            int ret = s.compare(sa[c], pattern_size, pattern);
            // patternが小さい
            if (ret <= 0) {
                left = c;
            }
            else {
                right = c;
            }
        }

        if (s.compare(sa[left], pattern_size, pattern) == 0) {
            return left;
        }
        return -1;
    }

    void debug() {
        std::cout << "idx lcp sa sa[i]" << std::endl;
        for (int i = 0; i <= n; ++i) {
            std::cout << i << " " << lcp[i] << " " << sa[i] << " " << s.substr(sa[i]) << std::endl;
        }
    }

private:
    struct compare {
        compare(const SuffixArray &sa) : sa(sa) {}
        const SuffixArray &sa;

        // (rank[i], rank[i + k])と(rank[j], rank[j + k])を比較
        bool operator()(const int &i, const int &j) const {
            if (sa.rank[i] != sa.rank[j]) {
                return sa.rank[i] < sa.rank[j];
            }
            else {
                const int ri = i + sa.k <= sa.n ? sa.rank[i + sa.k] : -1;
                const int rj = j + sa.k <= sa.n ? sa.rank[j + sa.k] : -1;
                return ri < rj;
            }
        }
    };

    void construct_sa() {
        std::vector<int> tmp(n + 1, 0);

        for (int i = 0; i <= n; i++) {
            sa[i] = i;
            rank[i] = i < n ? s[i] : -1;
        }
        // k文字についてソートされているところから、2k文字でソートする
        for (k = 1; k <= n; k *= 2) {
            sort(sa.begin(), sa.end(), compare(*this));
            // いったんtmpに次のランクを計算し、それからrankに移す
            tmp[sa[0]] = 0;
            for (int i = 1; i <= n; i++) {
                tmp[sa[i]] = tmp[sa[i - 1]] + (compare(*this).operator()(sa[i - 1], sa[i]) ? 1 : 0);
            }
            for (int i = 0; i <= n; i++) {
                rank[i] = tmp[i];
            }
        }
    }

    void construct_lcp() {
        for (int i = 0; i <= n; i++) {
            rank[sa[i]] = i;
        }
        int h = 0;
        lcp[0] = 0;
        for (int i = 0; i < n; i++) {
            // 文字列中での位置iの接尾辞と、接尾辞配列中でその1つ前の接尾辞のLCPを求める
            int j = sa[rank[i] - 1];
            // hを先頭の分1減らし、後ろが一致しているだけ増やす
            if (h > 0) {
                h--;
            }
            for (; j + h < n and i + h < n; h++) {
                if (s[j + h] != s[i + h]) {
                    break;
                }
            }
            lcp[rank[i] - 1] = h;
        }
    }
};


bool ok(int len, const string &S, const SuffixArray &sa) {
    if (len == 0) {
        return true;
    }
    int N = LEN(S);

    FOR(i, 0, N - len + 1) {
        string t;
        FOR(j, i, i + len) {
            t += S[j];
        }

        if (sa.find_last(t) >= i + len) {
            return true;
        }
    }
    return false;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    LL N;
    string S;
    cin >> N;
    cin >> S;

    SuffixArray sa(S);
    sa.build();


    // 開区間(low, high)で条件を満たす一番右
    long long low = -1;
    long long high = N;

    while (high - low > 1) {
        long long middle = (low + high) / 2;
        if (ok(middle, S, sa)) {
            low = middle;
        }
        else {
            high = middle;
        }
    }
    print(low);

    return 0;
}


Measured memory_bytes: 640