#include <bits/stdc++.h>
using namespace std;
int q[100010]={-1}, hh = 0, tt = 0,ans=0, n, m, a[100010], k = 0;
int main() {
    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        cin >> a[i];
        k = 0;
        for (int j = hh; j <= tt; j++) {
            if (a[i] == q[j]) {
                k = 1;
                break;
            }
        }if (k == 0) {
            q[tt++] = a[i];
            ans++;
            if(tt-hh>3)hh++;
        }
        //cout << ans << endl;
    }cout << ans;
    return 0;
}