#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
#include<bits/stdc++.h>
using namespace std;
#define rep(i,s,t) for(ll i = (ll)(s); i < (ll)(t); i++)
#define rrep(i,s,t) for(ll i = (ll)(s-1);(ll)(t) <= i; i--)
#define all(x) (x).begin(), (x).end()
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> Pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
constexpr ll INF = numeric_limits<ll>::max()/4;
constexpr ll n_max = 2e5+10;
#define int ll

template <typename A, typename B>
string to_string(pair<A, B> p);
string to_string(const string &s) {return '"' + s + '"';}
string to_string(const char c) {return to_string((string) &c);}
string to_string(bool b) {return (b ? "true" : "false");}
template <size_t N>
string to_string(bitset<N> v){
    string res = "";
    for(size_t i = 0; i < N; i++) res += static_cast<char>('0' + v[i]);
    return res;
}
template <typename A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for(const auto &x : v) {
        if(!first) res += ", ";
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p){return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";}

void debug_out() {cerr << endl;}
template<typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

template<class T>
bool chmax(T &a, T b){if(a < b){a = b; return true;} return false;}
template<class T>
bool chmin(T &a, T b){if(a > b){a = b; return true;} return false;}

const ll MS = 2;
const ll mod[] = {999999937LL, 1000000007LL}, base = 9937;

struct RollingHash {
    ll n;
    vector<ll> hs[MS], pw[MS];
    RollingHash(){};
    RollingHash(const string &s) {
        n = s.size();
        for(int i = 0; i < MS; i++){
            hs[i].assign(n+1, 0);
            pw[i].assign(n+1, 0);
            hs[i][0] = 0;
            pw[i][0] = 1;
            for(int j = 0;j < n; j++){
                pw[i][j + 1] = pw[i][j] * base % mod[i];
                hs[i][j+1] = (hs[i][j] * base + s[j]) % mod[i];
            }
        }
    }

    long long hash(int l, int r, int i){
        return ((hs[i][r] - hs[i][l] * pw[i][r-l]) % mod[i] + mod[i]) % mod[i];
    }

    bool match(int l1, int r1, int l2, int r2) {
        bool ret = true;
        for(int i = 0; i < MS; i++) ret &= hash(l1, r1, i) == hash(l2, r2, i);
        return ret;
    }

    bool match(int l, int r, long long h[]){
        bool ret = true;
        for(int i = 0; i < MS; i++) ret &= hash(l, r, i) == h[i];
        return ret;
    }
};

signed main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n; cin >> n;
    string s;cin >> s;
    RollingHash rh(s);
    auto c = [&](ll x){
        map<Pll, ll> mp;
        bool ok = false;
        rep(i,0,n){
            if(i + x > n)break;
            ll h1 = rh.hash(i, i + x, 0), h2 = rh.hash(i, i + x, 1);
            if(mp.count(Pll(h1, h2)) == 0){
                mp[Pll(h1, h2)] = i;
            }
            else{
                if(i - mp[Pll(h1, h2)] >= x)ok = true;
            }
        }
        return ok;
    };

    ll ng = n;
    ll ok = 0;
    while(abs(ok - ng) > 1){
        ll mid = (ok + ng) / 2;
        if(c(mid))ok = mid;
        else ng = mid;
    }

    cout << ok << endl;
}

Measured memory_bytes: 768