#include <bits/stdc++.h>
using namespace std;

using i8 = int8_t;
using i16 = int16_t;
using i32 = int32_t;
using i64 = int64_t;
using isize = ptrdiff_t;
using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using usize = size_t;
using f32 = float_t;
using f64 = double_t;

inline constexpr i32 Modulus = 1e9 + 7;

template <typename TScalar, typename... TRest>
inline constexpr TScalar Max(TScalar first, TRest... rest)
{
    static_assert((is_same_v<TScalar, TRest> && ...), "All arguments must have the same type");
    if constexpr (sizeof...(rest) == 0)
        return first;
    else
        return (first > Max(rest...)) ? first : Max(rest...);
}

int main(void)
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    usize n;
    cin >> n;

    usize longestLength = 0, startTime = 0;
    map<u32, usize> listenTimes;
    for (usize time = 0; time < n; time += 1)
    {
        u32 song;
        cin >> song;

        if (listenTimes.find(song) != listenTimes.end())
        {
            longestLength = Max(longestLength, time - startTime);
            startTime = Max(startTime, listenTimes[song] + 1);
        }

        listenTimes[song] = time;
    }

    cout << Max(longestLength, n - startTime);

    return 0;
}