#include <bits/stdc++.h>
#define REP(i, n)     for(int i = 0;i < n;i++)
#define REPR(i, n)    for(int i = n;i >= 0;i--)
#define FOR(i, m, n)  for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define VRSORT(v) sort(v.begin(), v.end(),greater<int>());
#define ALL(X) (X).begin(),(X).end()
#define INF 99999999
#define M_PI 3.14159265358979323846
#define MOD 1000000007

#ifdef __LOCAL
    #define DBG(X) cout << #X << " = " << (X) << endl;
    #define SAY(X) cout << (X) << endl;
#else
    #define DBG(X)
    #define SAY(X)
#endif

#ifdef __LOCAL
    #include <filesystem>
    namespace fs = std::filesystem;
#endif

using namespace std;

using ll = long long int;
using ull = unsigned long long int;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

int dx[]={1, 0, -1, 0, 0};
int dy[]={0, 1, 0, -1, 0};
const int INT_INF = (int)(2e9);
const ll  LL_INF = (ll)(2e18);
const int NIL = -1;
static mt19937 _g(time(nullptr));
 
std::string pad(int num){ char buffer[4]; std::snprintf(buffer, sizeof(buffer), "%03d", num); return buffer;}
inline ll randint(ll a, ll b) { ll w = (_g() << 31LL) ^ _g(); return a + w % (b - a + 1); }
inline void fast_io() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); };
template<typename T> inline T sign(T x) { return T(x > 0) - T(x < 0); }
template<typename T, typename S> inline ostream& operator<<(ostream& os, const pair<T, S> p) { cout << "[" << p.first << ";" << p.second << "]"; return os; }
template<typename T> inline ostream& operator<<(ostream& os, const vector<T>& v) { for (auto el : v) os << el << " "; return os; }
template<typename T> inline T fetch() { T ret; cin >> ret; return ret; }
template<typename T> inline vector<T> fetch_vec(int sz) { vector<T> ret(sz); for (auto& elem : ret) cin >> elem; return ret; }

int N;
string S;

vector< int > z_algorithm(const string &s) {
  vector< int > prefix(s.size());
  for(int i = 1, j = 0; i < s.size(); i++) {
    if(i + prefix[i - j] < j + prefix[j]) {
      prefix[i] = prefix[i - j];
    } else {
      int k = max(0, j + prefix[j] - i);
      while(i + k < s.size() && s[k] == s[i + k]) ++k;
      prefix[i] = k;
      j = i;
    }
  }
  prefix[0] = 0;
  return prefix;
}

void input(){
    fast_io();
    #ifdef __LOCAL
        fs::path p = __FILE__;
        fs::path input,output;
        input = output = p.parent_path();
        input += string("/input/") + string(p.stem()) + string(".txt");
        output += string("/output/") + string(p.stem()) + string(".txt");
        freopen(input.c_str(), "r", stdin);
        freopen(output.c_str(), "w", stdout);
    #endif
    cin >> N >> S;
}

// TLE
// 愚直にやった結果。TLE
void solve_0(){
    input();
    int ans=0;
    for(int len=1;len<=(N+1)/2;len++)
        for(int i=0;i+len<N;i++)
            for(int j=i+len;j+len<=N;j++){
                DBG(i);
                DBG(j);
                DBG(len);
                DBG(S.substr(i,len));
                DBG(S.substr(j,len));
                if(S.substr(i,len) == S.substr(j,len)){
                    ans = max(ans,len);
                }
            }
    cout << ans << endl;
}

void solve(){
    input();
    int ans=0;
    for(int i=0;i<S.size();i++){
        vector<int> A = z_algorithm(S.substr(i));
        for(int i=0;i<A.size();i++) A[i] = min(i,A[i]);
        ans = max(ans,*max_element(ALL(A)));
    }
    cout << ans << endl;
}


int main()
{
    solve();
    return 0;
}


Measured memory_bytes: 256