n,k=list(map(int,input().split()))
s=input()
a=list(map(str,input().split()))
d,f,p={},"",0
for i in range(k):
d[a[i]]=1
for i in range(n):
if d.get(s[i])!=None:
f+=s[i]
else:
g=len(f)
p+=(g*(g+1))//2
f=""
if f:
g=len(f)
p+=(g*(g+1))//2
print(p)#include<bits/stdc++.h>
using namespace std;
long long i,k,m,n,t,p[27];
char x;
string s;
int main(){
for(cin>>n>>k>>s;k--;p[x-96]=1)
cin>>x;
for(;i<=n;i++)
i<n&&p[s[i]-96]?m++:(t+=m*(m+1)/2,m=0);
cout<<t;
return 0;
}
71. Simplify Path | 62. Unique Paths |
50. Pow(x, n) | 43. Multiply Strings |
34. Find First and Last Position of Element in Sorted Array | 33. Search in Rotated Sorted Array |
17. Letter Combinations of a Phone Number | 5. Longest Palindromic Substring |
3. Longest Substring Without Repeating Characters | 1312. Minimum Insertion Steps to Make a String Palindrome |
1092. Shortest Common Supersequence | 1044. Longest Duplicate Substring |
1032. Stream of Characters | 987. Vertical Order Traversal of a Binary Tree |
952. Largest Component Size by Common Factor | 212. Word Search II |
174. Dungeon Game | 127. Word Ladder |
123. Best Time to Buy and Sell Stock III | 85. Maximal Rectangle |
84. Largest Rectangle in Histogram | 60. Permutation Sequence |
42. Trapping Rain Water | 32. Longest Valid Parentheses |
Cutting a material | Bubble Sort |
Number of triangles | AND path in a binary tree |
Factorial equations | Removal of vertices |