#include <queue>
#include <set>
using namespace std;

int main()
{
    int M, N;
    cin >> M >> N;
    queue<int> q;
    set<int> mem;
    int ans = 0;

    for(int i = 0; i < N; i++)
    {
        int x;
        cin >> x;
        if(mem.find(x) == mem.end())
        {
            ans++;
            // q.size()转int，消除signed/unsigned警告
            if((int)q.size() >= M)
            {
                int out = q.front();
                q.pop();
                mem.erase(out);
            }
            q.push(x);
            mem.insert(x);
        }
    }
    cout << ans << endl;
    return 0;
}