#include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <ctime>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <numeric>
#include <utility>
#include <iomanip>
#include <algorithm>
#include <functional>
#include <unordered_map>
using namespace std;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

template<class T> vector<T> make_vec(size_t a) { return vector<T>(a); }
template<class T, class... Ts> auto make_vec(size_t a, Ts... ts) {
  return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}
template<class T, class V>
typename enable_if<is_class<T>::value == 0>::type fill(T &t, const V &v) {
    t = v;
}
template<class T, class V>
typename enable_if<is_class<T>::value != 0>::type fill(T &t, const V &v){
    for (auto &e : t) fill(e, v);
}

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl
template<class T1, class T2> ostream& operator << (ostream &s, pair<T1,T2> P)
{ return s << '<' << P.first << ", " << P.second << '>'; }
template<class T> ostream& operator << (ostream &s, vector<T> P)
{ for (int i = 0; i < P.size(); ++i) { if (i > 0) { s << " "; } s << P[i]; } return s; }
template<class T> ostream& operator << (ostream &s, vector<vector<T> > P)
{ for (int i = 0; i < P.size(); ++i) { s << endl << P[i]; } return s << endl; }

#define EACH(i, s) for (__typeof__((s).begin()) i = (s).begin(); i != (s).end(); ++i)
template<class T> ostream& operator << (ostream &s, set<T> P)
{ EACH(it, P) { s << "<" << *it << "> "; } return s << endl; }
template<class T1, class T2> ostream& operator << (ostream &s, map<T1,T2> P)
{ EACH(it, P) { s << "<" << it->first << "->" << it->second << "> "; } return s << endl; }

// Sparse Table
template<class MeetSemiLattice> struct SparseTable {
    vector<vector<MeetSemiLattice> > dat;
    vector<int> height;
    
    SparseTable() { }
    SparseTable(const vector<MeetSemiLattice> &vec) { init(vec); }
    void init(const vector<MeetSemiLattice> &vec) {
        int n = (int)vec.size(), h = 0;
        while ((1<<h) < n) ++h;
        dat.assign(h, vector<MeetSemiLattice>(1<<h));
        height.assign(n+1, 0);
        for (int i = 2; i <= n; i++) height[i] = height[i>>1]+1;
        for (int i = 0; i < n; ++i) dat[0][i] = vec[i];
        for (int i = 1; i < h; ++i)
            for (int j = 0; j < n; ++j)
                dat[i][j] = min(dat[i-1][j], dat[i-1][min(j+(1<<(i-1)),n-1)]);
    }
    
    MeetSemiLattice get(int a, int b) {
        return min(dat[height[b-a]][a], dat[height[b-a]][b-(1<<height[b-a])]);
    }
};


// Suffix Array ( Manber&Myers: O(n (logn)^2) )
struct SuffixArray {
    string str;
    vector<int> sa;         // sa[i] : the starting index of the i-th smallest suffix (i = 0, 1, ..., n)
    vector<int> lcp;        // lcp[i]: the lcp of sa[i] and sa[i+1] (i = 0, 1, ..., n-1)
    inline int& operator [] (int i) {return sa[i];}
    
    SuffixArray(const string& str_) : str(str_) { buildSA(); calcLCP(); }
    void init(const string& str_) { str = str_; buildSA(); calcLCP(); }
    
    // build SA
    vector<int> rank_sa, tmp_rank_sa;
    struct CompareSA {
        int n, k;
        const vector<int> &rank;
        CompareSA(int n, int k, const vector<int> &rank_sa) : n(n), k(k), rank(rank_sa) {}
        bool operator()(int i, int j) {
            if (rank[i] != rank[j]) return (rank[i] < rank[j]);
            else {
                int rank_ik = (i + k <= n ? rank[i + k] : -1);
                int rank_jk = (j + k <= n ? rank[j + k] : -1);
                return (rank_ik < rank_jk);
            }
        }
    };
    void buildSA() {
        int n = (int)str.size();
        sa.resize(n+1), lcp.resize(n+1), rank_sa.resize(n+1), tmp_rank_sa.resize(n+1);
        for (int i = 0; i < n; ++i) sa[i] = i, rank_sa[i] = (int)str[i];
        sa[n] = n, rank_sa[n] = -1;
        for (int k = 1; k <= n; k *= 2) {
            CompareSA csa(n, k, rank_sa);
            sort(sa.begin(), sa.end(), csa);
            tmp_rank_sa[sa[0]] = 0;
            for (int i = 1; i <= n; ++i) {
                tmp_rank_sa[sa[i]] = tmp_rank_sa[sa[i - 1]];
                if (csa(sa[i - 1], sa[i])) ++tmp_rank_sa[sa[i]];
            }
            for (int i = 0; i <= n; ++i) rank_sa[i] = tmp_rank_sa[i];
        }
    }
    vector<int> rsa;
    SparseTable<int> st;
    void calcLCP() {
        int n = (int)str.size();
        rsa.resize(n+1);
        for (int i = 0; i <= n; ++i) rsa[sa[i]] = i;
        lcp.resize(n+1);
        lcp[0] = 0;
        int cur = 0;
        for (int i = 0; i < n; ++i) {
            int pi = sa[rsa[i] - 1];
            if (cur > 0) --cur;
            for (; pi + cur < n && i + cur < n; ++cur) {
                if (str[pi + cur] != str[i + cur]) break;
            }
            lcp[rsa[i] - 1] = cur;
        }
        st.init(lcp);
    }
    
    // calc lcp
    int getLCP(int a, int b) {          // lcp of str.sutstr(a) and str.substr(b)
        return st.get(min(rsa[a], rsa[b]), max(rsa[a], rsa[b]));
    }
};



int N;
string S;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    while (cin >> N >> S) {
        SuffixArray SA(S);

        int res = 0;
        for (int i = 0; i < N; ++i) {
            for (int j = i+1; j < N; ++j) {
                int l = SA.getLCP(i, j);
                chmin(l, j-i);
                chmin(l, N-j);
                chmax(res, l);
            }
        }
        cout << res << endl;
        
    }
}


















Measured memory_bytes: 768