#include <bits/stdc++.h>
using namespace std;
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T> using gpp_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename L> using gpp_map = tree<T, L, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using gpp_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;*/
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define bit_exist(x, n) ((x >> n) & 1)
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl;
#define mdebug(m) cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;}
#define pb push_back
#define f first
#define s second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void Ans(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using PiP = pair<int, Pii>;
using PPi = pair<Pii, int>;
using bools = vector<bool>;
using pairs = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;
//#define Add(x, y) x = (x + (y)) % mod
//#define Mult(x, y) x = (x * (y)) % mod

using ll = __int128_t;

struct RollingHash{

    static const ll MOD = 9223372036854775783;
    int N;
    ll x, invx;
    vector<ll> pow_x, pow_invx, hash_vec, invhash_vec;

    template<typename T>
    RollingHash(int x, vector<T> S, bool calcinv = false): x(x) {
        N = S.size();

        pow_x.resize(N + 1);
        pow_x[0] = 1;
        REP(i, N) pow_x[i + 1] = (pow_x[i] * x) % MOD;
        pow_invx.resize(N + 1);
        invx = inv();
        pow_invx[0] = 1;
        REP(i, N) pow_invx[i + 1] = (pow_invx[i] * invx) % MOD;

        hash_vec.resize(N + 1);
        hash_vec[0] = 0;
        REP(i, N) hash_vec[i + 1] = (hash_vec[i] + pow_x[i] * S[i]) % MOD;

        if(calcinv){
            invhash_vec.resize(N + 1);
            invhash_vec[N] = 0;
            REP(i, N) invhash_vec[N - 1 - i] = (invhash_vec[N - i] + pow_x[i] * S[N - 1 - i]) % MOD;
        }
    }

    RollingHash(int x, string S, bool calcinv = false){
        vector<int> s(S.size());
        REP(i, SZ(S)) s[i] = (int)S[i];
        *this = RollingHash(x, s, calcinv);
    }

    ll inv(){
        ll a = 1, n = MOD - 2;
        for(int i = 63; i >= 0; i--){ a = (a * a) % MOD; if((n >> i) & 1) a = (a * x) % MOD; }
        return a;
    }

    //0<=l<=r<N
    //Hash of (S_l,S_(l+1),...,S_r)
    ll hash(int l, int r){
        return (((hash_vec[r + 1] - hash_vec[l] + MOD) % MOD) * pow_invx[l]) % MOD;
    }

    //0<=l<=r<N
    //Hash of (S_r,S_(r-1),...,S_l)
    ll invhash(int l, int r){
        return (((invhash_vec[l] - invhash_vec[r + 1] + MOD) % MOD) * pow_invx[N - 1 - r]) % MOD;
    }

};

signed main(){

    int N; cin >> N;
    string S; cin >> S;
    RollingHash RH(1145141919, S);

    int l0 = 0, l1 = N + 1;
    while(l1 - l0 > 1){
        int l = (l0 + l1) / 2;
        bool f = false;
        queue<ll> que;
        map<ll, bool> exist;
        REP(i, N){
            if(i + l > N) break;
            while(SZ(que) >= l){
                exist[que.front()] = true;
                que.pop();
            }
            ll hash = RH.hash(i, i + l - 1);
            if(exist[hash]){
                f = true;
                break;
            }
            que.push(hash);
        }
        if(f) l0 = l;
        else l1 = l;
    }
    Out(l0);

    return 0;
}


Measured memory_bytes: 896