#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,_7,_8,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr8,pr7,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
#define prArr(a) {cerr<<(#a)<<"={";int i=0;for(auto t:(a))cerr<<(i++?", ":"")<<t;cerr<<"}"<<endl;}
using namespace std;
using Int = long long;
using _int = int;
using ll = long long;
using Double = long double;
const Int INF = (1LL<<60)+1e9; // ~ 1.15 * 1e18
const Int mod = (1e9)+7;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
using P = pair<Int,Int>;
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
template<class T1, class T2> ostream& operator<<(ostream& o,pair<T1,T2> p){return o<<"("<<p.first<<","<<p.second<<")";}
template<class T1, class T2, class T3> ostream& operator<<(ostream& o,tuple<T1,T2,T3> t){
  return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
template<class T1, class T2> istream& operator>>(istream& i,pair<T1,T2> &p){return i>>p.first>>p.second;}
template<class T> ostream& operator<<(ostream& o,vector<T> a){Int i=0;for(T t:a)o<<(i++?" ":"")<<t;return o;}
template<class T> istream& operator>>(istream& i,vector<T> &a){for(T &t:a)i>>t;return i;}
//INSERT ABOVE HERE
class RollingHash{
public:
  typedef long long ll;
  ll B, mod;  //B: ハッシュ基数
  Int n;
  string s;
  vector<ll> hash;
  vector<ll> k;

  RollingHash():n(-1){};
  RollingHash(string s,ll B = 1777771,ll mod = 1e9 + 7):
    B(B),mod(mod),n(s.size()),s(s),hash(n+1),k(n+1)
  {
    for(Int i=0;i<n;i++) hash[i+1] = (hash[i] * B % mod + s[i]) % mod;
    k[0] = 1;
    for(Int i=1;i<=n;i++) k[i] = (k[i-1] * B) % mod;
  }

  ll get(Int l,Int r)const{ //[l, r)
    assert(0<=l && r<=n && l<=r);
    return (mod + hash[r] - hash[l] * k[r-l] % mod) % mod;
  }

  //hash[a]とB.hash[b]からみて何文字一致してるか。
  Int count(Int a, const RollingHash &B, Int b){
    Int L = 0, R = min( n - a, B.n - b ) + 1;
    while( L + 1 < R ){
      Int M = ( L + R ) / 2;
      get( a, a + M ) != B.get( b, b + M ) ? R = M : L = M;
    }
    return L;
  }
};

class MultiCompareRollingHash{
public:
  typedef long long ll;
  Int n = 5;
  vector<RollingHash> A;
  vector<ll> B = {10000019, 10000079, 10000103, 10000121, 10000139};
  vector<ll> mod = {1000000007, 1000000009, 1000000021, 1000000033, 1000000087};

  MultiCompareRollingHash(){}
  MultiCompareRollingHash(string s){
    A.resize(n);
    assert(n <= (Int)mod.size());
    assert(n <= (Int)B.size());
    assert(B.size() == mod.size());
    for(Int i=0;i<n;i++) A[i] = RollingHash(s, B[i], mod[i]);
  }

  ll get(Int i,Int l,Int r){return A[i].get(l, r);}

  vector<ll> get(Int l,Int r){
    vector<ll> res;
    for(Int i=0;i<n;i++) res.push_back(get(i, l, r));
    return res;
  }

  Int eq(Int l1,Int r1,Int l2,Int r2){
    for(Int i=0;i<n;i++) if(get(i, l1, r1) != get(i, l2, r2)) return 0;
    return 1;
  }
};


signed main(){
  srand((unsigned)time(NULL));
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  Int N;
  cin>>N;
  string S;
  cin>>S;

  MultiCompareRollingHash rh(S);
  auto check=[&](Int X){
    using P = pair<vector<ll>, Int>;
    set<P> Hash;

    for(Int i=0;i<N;i++){
      if(i + X > N) continue;
      auto hash = rh.get(i, i+X);
      Hash.insert(P(hash, i));
    }

    for(Int i=0;i<N;i++){
      if(i + X > N) continue;
      auto hash = rh.get(i, i+X);
      auto it = Hash.upper_bound(P(hash, i+X-1));
      if(it != Hash.end() && it->first == hash) return 1;
    }
    return 0;
  };

  Int L = 0, R = N;
  while(L + 1 < R){
    Int M = (L + R) / 2;
    if(check(M)) L = M;
    else R = M;
  }

  Int ans = L;
  cout<<ans<<endl;


  return 0;
}


Measured memory_bytes: 1280