#include <bits/stdc++.h>
using namespace std;
 
#define S second
#define F first
#define LL long long 
#define LINF 100000000000000000
#define INF 1000000000
 
const int N = 4e5+10;
const LL MOD = 1e9+7;

map<int,int>mp,mp1;
vector<int>vec;

int main()
{      
    //freopen("out.txt","w",stdout);

    int n;
    scanf("%d",&n);

    for(int i=1;i<=n;i++){
        int x;cin>>x;
        vec.push_back(x);
        mp[x] = max(mp[x],i);
        if(!mp1[x])mp1[x] = i;
        else mp1[x] = min(mp1[x],i);
    }

    int ans = 0;
    for(auto x:vec)
        ans = max(ans,mp[x]-mp1[x]+1);
    
    printf("%d\n",ans);
}