#include <stdio.h>

#include <string.h>

const int N = ;

const int MAX_N = ;

int hash[MAX_N];

char A[N];

int value[];

int main( )

{

    int N, NC, hashVal, valueKey = ;

    int len, ans = , Count = ;

    memset( value, , sizeof( value ) );

    memset( A, , sizeof( A ) );

    memset( hash, , sizeof( hash ) );

    scanf( "%d %d\n", &N, &NC );

    scanf( "%s", A );

    len = strlen( A );

    for ( int i = ; i < len; ++i )

    {

        if ( value[A[i]] ==  )

            value[A[i]] = ++valueKey;

        if ( valueKey == NC )

            break;

    }

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

    {

        hashVal = ;

        for ( int j = i; j < i + N; ++j )

            hashVal = hashVal * NC + value[A[j]] - ;

        if ( hash[hashVal] ==  )

        {

            hash[hashVal] = ;

            ans++;

        }

    }

    printf( "%d\n", ans );

    return ;

}