#include <bits/stdc++.h>
using namespace std;

int main(){
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    string g, s;
    cin >> g >> s;
    map<char, int> a;
    for(int i = 0; i < n; i++)
        a[g[i]]++;

    int ans = 0;
    for(int i = 0; i < m; i++){
        //cerr << i << " " << a.size() << endl;
        a[s[i]]--;
        //cerr << "- " << s[i] << " " << a[s[i]] << endl;
        if(i >= n){
            a[s[i-n]]++;
            //cerr << "+ " << s[i-n] << " " << a[s[i-n]] << endl;
            if(a[s[i-n]] == 0)
                a.erase(a.find(s[i-n]));
        }
        if(a[s[i]] == 0)
            a.erase(a.find(s[i]));
        if(a.size() == 0)
            ans++;
    }

    cout << ans;

    return 0;
}