#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> vec;
typedef vector<vec> mat;
#define rep(i, n) for(ll i = 0; i < (n); i++)
#define revrep(i, n) for(ll i = (n)-1; i >= 0; i--)
#define pb push_back
#define f first
#define s second
/*
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll max3(ll a, ll b, ll c){return max(a, max(b, c));};
ll min3(ll a, ll b, ll c){return min(a, min(b, c));};
ll max4(ll a, ll b, ll c, ll d){return max(max(a, b), min(c, d));};
ll min4(ll a, ll b, ll c, ll d){return min(min(a, b), min(c, d));};
ll max5(ll a, ll b, ll c, ll d, ll e){return max(max(a, b), max3(c, d, e));};
ll min5(ll a, ll b, ll c, ll d, ll e){return min(min(a, b), min3(c, d, e));};
*/
const ll INFL = 1LL << 60;//10^18 = 2^60
const int INF = 1 << 30;//10^9
ll MOD = 1000000007;
//ll MOD = 998244353;

vector<ll> dy = {0, 0, 1, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, -1, 0, 0, 1, -1, 1, -1, 0};


ll pow_long(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2) res *= x;
    x *= x;
    k /= 2;
  }
  return res;
}
ll pow_mod(ll x, ll k){
  x %= MOD; x += MOD; x %= MOD;
  ll res = 1;
  while(k > 0){
    if(k % 2){
      res *= x; res %= MOD;
    }
    x *= x; x %= MOD;
    k /= 2;
  }
  return res;
}

ll inverse(ll x){return pow_mod(x, MOD - 2);};

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

ll lcm(ll x, ll y){return x / gcd(x, y) * y;};

ll kai_mod(ll x){
  if(x == 0) return 1;
  return x * kai_mod(x-1) % MOD;
}

/*
//コンビネーション
const int MAXcomb = 200010;
ll fac[MAXcomb], finv[MAXcomb], inv[MAXcomb];
//facはn!,finvは1/n!
//invは逆元
void COMinit(){
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for(int i = 2; i < MAXcomb; i++){
        fac[i] = fac[i-1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD/i) % MOD;
        finv[i] = finv[i-1] * inv[i] % MOD;
    }
}
ll comb(int n, int k){
    if(n < k) return 0;
    if(n < 0 || k < 0) return 0;
    return fac[n] * finv[k] % MOD * finv[n-k] % MOD;
}
*/

struct RollingHash{
  string S;
  ll sl;//Sのサイズ
  vector<ll> hashed, power;
  ll base = 998244353;
  ll mod = 1000000007;
  void getS(string s){
    S = s;
    sl = S.size();
    hashed.resize(sl + 1, 0);
    power.resize(sl + 1);
    power[0] = 1;
    rep(i, sl){
      power[i+1] = (power[i] * base) % mod;
      hashed[i+1] = (hashed[i] * base + S[i]) % mod;
    }
  }

  ll getHash(ll l, ll r){
    ll res = ((hashed[r] - hashed[l] * power[r-l]) % mod + mod) % mod;
    return res;
  }

  //使ったことない
  ll connect(ll hash1, ll hash2, ll hash2size){
    ll res = (hash1 * power[hash2size] + hash2) % mod;
    return res;
  }
};


ll N;
string S;
RollingHash RH;
ll solve(ll s, ll b){
  RH.mod = s;
  RH.base = b;
  RH.getS(S);
  ll ok = 0, ng = min(N, N/2+1);
  while(ng - ok > 1){
    ll mid = (ok + ng) / 2;
    bool l = 0;
    set<ll> used;
    queue<ll> lazy;
    rep(i, N-mid+1){//スタート地点
      //if(l) break;
      ll hash = RH.getHash(i, i+mid);
      if(used.count(hash)) l = 1;
      lazy.push(hash);
      if(i >= mid - 1){
        ll plus = lazy.front();
        lazy.pop();
        used.insert(plus);
      }
    }
    if(l){
      ok = mid;
    }else{
      ng = mid;
    }
  }
  return ok;
}

int main(){
  cin >> N >> S;
  vector<ll> ans;
  vector<ll> sosuu = {1000000007, 100000007, 1000000009, 999999883, 999999893};
  vector<ll> base = {999999929, 999999937};
  rep(i, sosuu.size()){
    rep(j, base.size()){
      ans.pb(solve(sosuu[i], base[j]));
    }
  }
  sort(ans.begin(), ans.end());
  cout << ans[5] << endl;
}


Measured memory_bytes: 624