#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e6;
int n, m, idx[MAXN + 5], s[2 * MAXN + 5], lt[MAXN + 5], rt[MAXN + 5], pi[2 * MAXN + 5];
struct linked_list {
int n, *l, *r;
linked_list(int n_) :
n(n_), l(new int[n_ + 5]), r(new int[n_ + 5]) {
for (int i = 1; i <= n; i++) {
l[i] = i - 1;
r[i] = i + 1;
}
}
void del(int i) {
int l_ = l[i], r_ = r[i];
r[l_] = r_;
l[r_] = l_;
}
};
bool check(int i, int j) {
if (i == n + 1) return false;
if (lt[i] && s[j - i + lt[i]] > s[j])
return false;
if (rt[i] && s[j + rt[i] - i] < s[j])
return false;
return true;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> idx[i];
s[idx[i]] = i;
}
s[n + 1] = 0;
for (int i = n + 2; i <= n + 1 + m; i++)
cin >> s[i];
linked_list lk(n);
for (int i = n; i >= 1; i--) {
lt[i] = idx[lk.l[s[i]]];
rt[i] = idx[lk.r[s[i]]];
lk.del(s[i]);
}
int ans = 0;
for (int i = 2; i <= n + m + 1; i++) {
if (i == n + 1) continue;
int tmp = pi[i - 1];
while (tmp > 0 && !check(tmp + 1, i))
tmp = pi[tmp];
if (check(tmp + 1, i)) pi[i] = tmp + 1;
if (i > n + 1 && pi[i] == n) ans++;
}
// for (int i = 1; i <= n; i++)
// cout << s[i] << " ";
// cout << '\n';
// for (int i = 1; i <= n; i++) {
// cout << "phan tu " << i << " : " << lt[i] << ", " << rt[i] << '\n';
// }
// for (int i = n + 2; i <= n + m + 1; i++)
// cout << pi[i] << " ";
// cout << '\n';
cout << ans;
}
