import std.algorithm;
import std.array;
import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

int readint() { return readln.chomp.to!int; }
int[] readints() { return readln.split.to!(int[]); }

int calc(int[] xs) {
    bool[int] used = [xs[0]: true];
    int[] q = [xs[0]];
    int ans = 1;
    foreach (x; xs) {
        while (x in used) {
            used.remove(q[0]);
            q = q[1..$];
        }

        used[x] = true;
        q ~= x;
        ans = max(ans, cast(int)q.length);
    }
    return ans;
}

void main() {
    readint;
    auto xs = readints;
    auto ans = calc(xs);
    writeln(ans);
}