#include<bits/stdc++.h>
using namespace std;

#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define lfs <<fixed<<setprecision(10)<<
#define test cout<<"test"<<endl;
#define fi first
#define se second
#define MP make_pair
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = n; i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = n - 1; i >= (ll)(m); i--)
typedef long long ll;
typedef long double ld;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template<typename T>
void chmin(T &a,T b){if(a>b)a=b;}
template<typename T>
void chmax(T &a,T b){if(a<b)a=b;}
void pmod(ll &a,ll b){a=(a+b)%MOD;}
void pmod(ll &a,ll b,ll c){a=(b+c)%MOD;}
void qmod(ll &a,ll b){a=(a*b)%MOD;}
void qmod(ll &a,ll b,ll c){a=(b*c)%MOD;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>
void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T>
void debug(vector<vector<T>>v,ll h,ll w){for(ll i=0;i<h;i++)
{cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>v,ll h,ll w){for(ll i=0;i<h;i++)
{for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
template<typename T>
void debug(vector<T>v,ll n){cout<<v[0];
for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
template<typename T>
vector<vector<T>>vec(ll x, ll y, T w){
  vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
template<typename T>
void emp(map<T,ll>&m, T x){m.emplace(x,0).first->second++;}
vector<ll>dx={1,0,-1,0,1,1,-1,-1};
vector<ll>dy={0,1,0,-1,1,-1,1,-1};

template<ll mod1,ll mod2>
struct RollingHash{
  vector<ll> hash1,p1,hash2,p2;
  ll base;
  RollingHash(string s, ll b){
    ll n = (ll)s.size();
    base = b;
    hash1.assign(n+1,0);
    hash2.assign(n+1,0);
    p1.assign(n+1,1);
    p2.assign(n+1,1);
    for(ll i=0;i<n;i++){
      hash1[i+1]=(hash1[i]*base+s[i])%mod1;
      hash2[i+1]=(hash2[i]*base+s[i])%mod2;
      p1[i+1]=(p1[i]*base)%mod1;
      p2[i+1]=(p2[i]*base)%mod2;
    }
  }
  P get(ll l, ll r){
    ll ret1=hash1[r+1]-(hash1[l]*p1[r-l+1])%mod1;
    ll ret2=hash2[r+1]-(hash2[l]*p2[r-l+1])%mod2;
    if(ret1<0)ret1+=mod1;
    if(ret2<0)ret2+=mod2;
    return MP(ret1,ret2);
  }
};


int main(){
  cin.tie(NULL);
  ios_base::sync_with_stdio(false);
  ll res=0,res1=INF,res2=-INF,buf=0;
  bool judge = true;
  const ll tmp_mod1=608396398;
  const ll tmp_mod2=979418779;
  //const ll tmp_mod=775791517;
  ll base=0;while(base<100000)base=(rand()*rand()*998244353)%min(tmp_mod1,tmp_mod2);
  //ll base = 100000;
  using RH = RollingHash<tmp_mod1,tmp_mod2>;
  ll n;cin>>n;
  string s;cin>>s;
  RH rh(s,base);
  rep(i,0,n-1)rep(j,i+1,n){
    ll l=i-1,r=j;
    while(r-l>=2){
      ll mid=(l+r)/2;
      if(j+mid-i>=n||rh.get(i,mid)!=rh.get(j,j+mid-i)){
        r=mid;
      }
      else l=mid;
    }
    chmax(res,l-i+1);
  }
  cout<<res<<endl;
  return 0;
}

Measured memory_bytes: 384