#include <bits/stdc++.h>   using namespace std;   int main() {     int n, k;     cin >> n >> k;     string s;     cin >> s;     bool arr[26] = {false};     for (int i = 0; i < k; i++) {       char c;       cin >> c;       arr[c -  a ] = true;     }     long long ans = 0;     long long co = 0;     for (int i = 0; i < n; i++) {       int x;       x = s[i] -  a ;       if (arr[s[i] -  a ] == true)         co++;       else {         ans += (co * (co + 1)) / 2;         co = 0;       }     }     ans += (co * (co + 1)) / 2;     cout << ans;   }   