#include <iostream>
#include <iomanip>
#include <string>
#include <stack>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <iterator>
#include <map>
#include <set>
#include <queue>
#include <list>
using namespace std;
using pii  = pair<int,int>;
using ll=long long;
using ld=long double;
#define pb push_back
#define mp make_pair
#define stpr setprecision
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define rep(i,n) for(ll i=0;i<(n);++i)
#define Rep(i,a,b) for(ll i=(a);i<(b);++i)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define rRep(i,a,b) for(int i=a;i>=b;i--)
#define crep(i) for(char i='a';i<='z';++i)
#define psortsecond(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.second<b.second;});
#define ALL(x) (x).begin(),(x).end()
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define endl '\n'
int ctoi(const char c){
  if('0' <= c && c <= '9') return (c-'0');
  return -1;
}
ll gcd(ll a,ll b){return (b == 0 ? a : gcd(b, a%b));}
ll lcm(ll a,ll b){return a*b/gcd(a,b);}
constexpr ll MOD=1000000007;
constexpr ll INF=1000000011;
constexpr ll MOD2=998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS=10e-8;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> istream& operator>>(istream& is,vector<T>& v){for(auto&& x:v)is >> x;return is;}
template<typename T,typename U> istream& operator>>(istream& is, pair<T,U>& p){ is >> p.first; is >> p.second; return is;}
template<typename T,typename U> ostream& operator>>(ostream& os, const pair<T,U>& p){ os << p.first << ' ' << p.second; return os;}
template<class T> ostream& operator<<(ostream& os, vector<T>& v){
  for(auto i=begin(v); i != end(v); ++i){
    if(i !=begin(v)) os << ' ';
    os << *i;
  }
  return os;
}

// ローリングハッシュ
// 二分探索で LCP を求める機能つき
struct RollingHash {
  static const int base1 = 1007, base2 = 2009;
  static const int mod1 = 1000000007, mod2 = 1000000009;
  vector<long long> hash1, hash2, power1, power2;

  // construct
  RollingHash(const string &S) {
    int n = (int)S.size();
    hash1.assign(n+1, 0);
    hash2.assign(n+1, 0);
    power1.assign(n+1, 1);
    power2.assign(n+1, 1);
    for (int i = 0; i < n; ++i) {
      hash1[i+1] = (hash1[i] * base1 + S[i]) % mod1;
      hash2[i+1] = (hash2[i] * base2 + S[i]) % mod2;
      power1[i+1] = (power1[i] * base1) % mod1;
      power2[i+1] = (power2[i] * base2) % mod2;
    }
  }
    
  // get hash of S[left:right]
  inline pair<long long, long long> get(int l, int r) const {
    long long res1 = hash1[r] - hash1[l] * power1[r-l] % mod1;
    if (res1 < 0) res1 += mod1;
    long long res2 = hash2[r] - hash2[l] * power2[r-l] % mod2;
    if (res2 < 0) res2 += mod2;
    return {res1, res2};
  }

  // get lcp of S[a:] and T[b:]
  inline int getLCP(int a, int b) const {
    int len = min((int)hash1.size()-a, (int)hash1.size()-b);
    int low = 0, high = len;
    while (high - low > 1) {
      int mid = (low + high) >> 1;
      if (get(a, a+mid) != get(b, b+mid)) high = mid;
      else low = mid;
    }
    return low;
  }
  inline bool same(int a, int b, int x) const {
    if (get(a, a+x) != get(b, b+x)) return 0;
    return 1;
  }
};

int main() { 
  int N;
  string S;
  cin >> N;
  cin >> S;
  // ロリハ
  RollingHash rh(S);
  // 求める
  ll ng = S.size();
  ll ok = 0;
  while(ng-ok>1){
    ll T=0;
    ll mid = (ok+ng)/2;
    rep(i,S.size()){
      Rep(j,i+mid,S.size()){
        if(rh.same(i,j,mid)){
          T=1;
          break;
        }
      }
    }
    if(T==1){
      ok = mid;
    }
    else{
      ng = mid;
    }
  }  
  cout << ok << endl;
}

Measured memory_bytes: 512