#include <iostream>

#include <cstring>

#include <string>

#include <queue>

#include <vector>

#include <map>

#include <set>

#include <stack>

#include <cmath>

#include <cstdio>

#include <algorithm>

#include <iomanip>

#include <stdlib.h>

#include <time.h>

#define LL long long

using namespace std;

const LL mod = ;

const LL N = ;

class SF

{

    //N:数组大小

public:

    int x[N], y[N], c[N];

    int Height[N],str[N], SA[N], Rank[N];//Height数组从2开始

    int slen;

    int m=;//字符集处理大小(传入如果不是数字，需要做位移转换)

    bool cmp(int* r, int a, int b, int l) {

        return r[a] == r[b] && r[a + l] == r[b + l];

    }

    void Suffix(int n) {

        ++n;

        int i, j, p;

        for (i = ; i < m; ++i) c[i] = ;

        for (i = ; i < n; ++i) c[x[i] = str[i]]++;

        for (i = ; i < m; ++i) c[i] += c[i - ];

        for (i = n - ; i >= ; --i) SA[--c[x[i]]] = i;

        for (j = ; j <= n; j <<= ) {

            p = ;

            for (i = n - j; i < n; ++i) y[p++] = i;

            for (i = ; i < n; ++i) if (SA[i] >= j) y[p++] = SA[i] - j;

            for (i = ; i < m; ++i) c[i] = ;

            for (i = ; i < n; ++i) c[x[y[i]]]++;

            for (i = ; i < m; ++i) c[i] += c[i - ];

            for (i = n - ; i >= ; --i) SA[--c[x[y[i]]]] = y[i];

            swap(x, y);

            p = ; x[SA[]] = ;

            for (i = ; i < n; ++i) {

                x[SA[i]] = cmp(y, SA[i - ], SA[i], j) ? p -  : p++;

            }

            if (p >= n)break;

            m = p;

        }

        int k = ;

        n--;

        for (i = ; i <= n; ++i) Rank[SA[i]] = i;

        for (i = ; i < n; ++i) {

            if (k)--k;

            j = SA[Rank[i] - ];

            while (str[i + k] == str[j + k])++k;

            Height[Rank[i]] = k;

            //cout << k << endl;

        }

    }

    void init(vector<int> &vv)

    {

        slen = vv.size();

        for (int i = ; i < slen; i++)

            str[i] = vv[i]+;//如果是字符，映射成从1开始的序列

        str[slen] = ;//0作为结束符，防止越界

        Suffix(slen);

    }

    struct nod

    {

        int mx, mi;

    };

    int ans;

    bool ok(int k)

    {

        int temp = ;

        int mx = , mi = ;

        bool f = false;

        for (int i = ; i <= slen; i++)

        {

            if (Height[i] >= k)

            {

                mx = max(mx, max(SA[i - ], SA[i]));

                mi = min(mi, min(SA[i - ], SA[i]));

            }

            else

            {

                mx = ;

                    mi = ;

            }

            if (mx - mi >= k)f = true;

        }

        return f;

    }

    int go(int l, int r)

    {

        for (; r >= l; r--)

            if (ok(r))return r;

        return ;

    }

    int bins(int l, int r)

    {

        while (l <= r)

        {

            if(r-l<=)

                return go(l, r);

            int mid = (l + r) / ;

            if (ok(mid))

                l = mid;

            else r = mid - ;

        }

    }

    LL solve()

    {

        ans=bins(, slen);

        return ans;

    }

}sf;

LL dp[][];

LL n;

int main() {

    cin.sync_with_stdio(false);

    while (cin >> n)

    {

        vector<int> v;

        for (int i = ; i < n; i++)

        {

            int num;

            cin >> num;

            v.push_back(num);

        }

        sf.init(v);

        cout << sf.solve() << endl;

    }

    return ;

}