// yukicoder: No.3009 異なる数字の最大の範囲
// 2019.6.28 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif

int in() {
	int n = 0, c = gc();
	while (c < '0') c = gc();
	do n = 10 * n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

int N;
int  a[100005];
char f[1000005];

int main()
{
	int i, k, ans;

	N = in(); for (i = 0; i < N; i++) a[i] = in();
	a[N] = a[N-1];
	k = 0, ans = 0, f[a[0]] = 1, i = 1;
	while (i < N) {
		while (!f[a[i]]) f[a[i++]] = 1;
		if (i >= N) break;
		if (i-k > ans) ans = i - k;
		while (a[k] != a[i]) f[a[k++]] = 0;
		k++, i++;
	}
	if (i-k > ans) ans = i - k;
	printf("%d\n", ans);
	return 0;
}