#include <algorithm>
#include <functional>

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <map>
#include <vector>
#include <string>

using namespace std;

const int MAXN = 1000100; // 10^6
const int inf = 1000000100;

int n;
int A[ MAXN ];
int Zadnje[ MAXN ];

int main( void )
{
    int T = 1;

    for( int counter = 0; counter < T; ++counter ) {
        scanf( "%d", &n );
        map< int, int > last;

        for( int i = 0; i < n; ++i ) {
            scanf( "%d", A + i );

            if( last.count( A[i] ) )
                Zadnje[i] = last[ A[i] ];
            else
                Zadnje[i] = -inf;
            
            last[ A[i] ] = i;
        }

        int pocetak = 0;
        int maks = 0;

        for( int i = 0; i < n; ++i ) {
            if( Zadnje[i] >= pocetak ) pocetak = Zadnje[i] + 1;
            if( i-pocetak+1 >= maks ) maks = i-pocetak+1;
        }

        printf( "%d\n", maks );
    }

    return (0-0);
}