NUC_TeamTEST

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int max_size = 100000+10;

int main()
{
    int n, k;
    char str[max_size];
    long long  arry[26];
    while(scanf("%d %d", &n, &k) == 2)
    {
        getchar();
        memset(arry, 0, sizeof(arry));
        scanf("%s", str);
        int len = strlen(str);
        int i;
        for(i = 0; i < len; ++i)
        {
            arry[str[i]-‘A‘]++;
        }
        i = 25;
        sort(arry, arry+26);
        //printf("%d\n", arry[25]);
        long long sum = 0;
        long long now = k;
        do{
            if(now > arry[i])
            {
                sum += arry[i] * arry[i];
                now -= arry[i];
                //printf("%d\n", sum);
                i--;
            }else if(now <= arry[i]){
                sum += now*now;          ///这个比较坑，没考虑到超int
                break;
            }
        }while(now != 0);
        cout << sum << endl;
    }
    return 0;
}