e289

/* e289              */
/* AC (0.2s, 64.6MB) */
#pragma warning( disable : 4996 )
#include <iostream>
#include <string>
#include <unordered_map>

using namespace std;

unordered_map <string, long long> umap;
long long n, m, l = 0, r = 0, cata = 0, ans = 0;
string s[200001];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);

    cin >> m >> n;
    for (int i = 0; i < n && cin >> s[i]; ++i);

    for (int i = 0; i < m; ++i)
    {
        if (!umap[s[i]])
            ++cata;
        ++umap[s[i]];
    }

    l = 0, r = m;
    for (; r <= n;)
    {
        ans += (m == cata);

        if (--umap[s[l]] == 0)
            --cata;

        if (umap[s[r]]++ == 0)
            ++cata;

        ++l, ++r;
    }
    cout << ans;
    return 0;
}