#include <set>

 #include <map>

 #include <cmath>

 #include <queue>

 #include <vector>

 #include <cstdio>

 #include <cstdlib>

 #include <cstring>

 #include <iostream>

 #include <algorithm>

 using namespace std;

 const int MAXN=;

 char s[MAXN];int hash[MAXN],num[];

 int main(){

     for(int N,NC;scanf("%d%d",&N,&NC)!=EOF;){

         memset(hash,,sizeof(hash));

         memset(num,,sizeof(num));

         scanf("%s",s+);

         int cnt=,ans=,len=strlen(s+);

         for(int i=;i<=len&&cnt<=NC;i++)if(!num[s[i]])num[s[i]]=cnt++;

         for(int i=;i<=len-N+;i++){

             int hashi=;for(int j=i;j<=i+N-;j++)hashi=hashi*NC+num[s[j]];

             hash[hashi]?:ans++,hash[hashi]=;

         }

         cout<<ans<<endl;

     }

     return ;

 }