#include<iostream>

using namespace std;

int m[1001], first, last, M, N, num;

int main() {
	cin >> M >> N;
	for (int i = 0; i < N; i++) {
		int w, j;
		cin >> w;
		for (j = first; j < last && m[j] != w; j++) {}
		if (j == last) {
			m[last] = w;
			last++;
			num++;
		}
		if (last - first > M)
			first++;
	}
	cout << num;
	return 0;
}