#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
// stdout
#include <stdio.h>
// mmap
#include <sys/mman.h>

// clang-format off
#define RD(v) int v=0;{int _c;while(_c=*rp++-48,_c>=0)v=v*10+_c;}
#define wt_int(var, buf, ptr) while(var){buf[ptr++]=var%10;var/=10;}while(ptr--)putc_unlocked(buf[ptr]+'0',stdout);
// clang-format on

int cnt[1000001];
int a[100000];

int main() {
    char *rp = mmap(0l, 1l << 28, 1, 2, 0, 0ll);
    RD(n);
    int *ap = a;
    for (int i = 0; i < n; ++i) {
        RD(t);
        *ap++ = t;
    }

    int *left = a;
    int ma = 0;
    for (int *right = a; right < ap; ++right) {
        ++cnt[*right];
        while (cnt[*right] > 1) cnt[*left++]--;
        if (right - left + 1 > ma) ma = right - left + 1;
    }

    char buf[7];
    n = 0;
    wt_int(ma, buf, n);
    return 0;
}