#include <iostream>#include <cstdio>#include <cstdlib>#include <cmath>#include <algorithm>#include <climits>#include <cstring>#include <string>#include <set>#include <map>#include <unordered_map>#include <queue>#include <stack>#include <vector>#include <list>#define rep(i,m,n) for(i=m;i<=n;i++)#define rsp(it,s) for(set<int>::iterator it=s.begin();it!=s.end();it++)#define mod 1000000007#define inf 0x3f3f3f3f#define vi vector<int>#define pb push_back#define mp make_pair#define fi first#define se second#define ll long long#define pi acos(-1.0)#define pii pair<int,int>#define Lson L, mid, ls[rt]#define Rson mid+1, R, rs[rt]#define sys system("pause")#define freopen freopen("in.txt","r",stdin)const int maxn=1e5+10;using namespace std;ll gcd(ll p,ll q){return q==0?p:gcd(q,p%q);}ll qpow(ll p,ll q){ll f=1;while(q){if(q&1)f=f*p;p=p*p;q>>=1;}return f;}inline ll read(){    ll x=0;int f=1;char ch=getchar();    while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}    while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘;ch=getchar();}    return x*f;}int n,m,k,t,cntA[maxn],cntB[maxn],sa[maxn],lev[maxn],ch[maxn],height[maxn],A[maxn],B[maxn],tsa[maxn];void solve(){    for (int i = 0; i < 1001; i ++) cntA[i] = 0;    for (int i = 1; i <= n; i ++) cntA[ch[i]] ++;    for (int i = 1; i < 1001; i ++) cntA[i] += cntA[i - 1];    for (int i = n; i; i --) sa[cntA[ch[i]] --] = i;    lev[sa[1]] = 1;    for (int i = 2; i <= n; i ++)    {        lev[sa[i]] = lev[sa[i - 1]];        if (ch[sa[i]] != ch[sa[i - 1]]) lev[sa[i]] ++;    }    for (int l = 1; lev[sa[n]] < n; l <<= 1)    {        for (int i = 0; i <= n; i ++) cntA[i] = 0;        for (int i = 0; i <= n; i ++) cntB[i] = 0;        for (int i = 1; i <= n; i ++)        {            cntA[A[i] = lev[i]] ++;            cntB[B[i] = (i + l <= n) ? lev[i + l] : 0] ++;        }        for (int i = 1; i <= n; i ++) cntB[i] += cntB[i - 1];        for (int i = n; i; i --) tsa[cntB[B[i]] --] = i;        for (int i = 1; i <= n; i ++) cntA[i] += cntA[i - 1];        for (int i = n; i; i --) sa[cntA[A[tsa[i]]] --] = tsa[i];        lev[sa[1]] = 1;        for (int i = 2; i <= n; i ++)        {            lev[sa[i]] = lev[sa[i - 1]];            if (A[sa[i]] != A[sa[i - 1]] || B[sa[i]] != B[sa[i - 1]]) lev[sa[i]] ++;        }    }    for (int i = 1, j = 0; i <= n; i ++)    {        if (j) j --;        while (ch[i + j] == ch[sa[lev[i] - 1] + j]) j ++;        height[lev[i]] = j;    }}bool check(int p){    int ma,mi;    for(int i=1;i<=n;i++)    {        if(height[i]<p)        {            ma=sa[i];            mi=sa[i];        }        else        {            ma=max(ma,sa[i]);            mi=min(mi,sa[i]);            if(ma-mi>=p)return true;        }    }    return false;}int main(){    int i,j;    scanf("%d",&n);    rep(i,1,n)ch[i]=read();    solve();    int l=1,r=n/2,ans=0;    while(l<=r)    {        int mid=l+r>>1;        if(check(mid))ans=mid,l=mid+1;        else r=mid-1;    }    printf("%d\n",ans);    //system("Pause");    return 0;}