#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7,N = 1e6+9;
typedef long long ll;
int n,m,res;
queue<int>q;
bool a[N];
int main()
{
    cin >> n>>m;
    for (int i = 1; i <= m; i++)
    {
        int x;
        cin >> x;
        if (a[x])continue;     
        else
        {
            if (q.size() >= n)
            {
                a[q.front()] = false;
                q.pop();
            }
            q.push(x);
            a[x] = true;
            res++;
        }
    }
    cout << res;
    return 0;
}