Appleman has n cards. Each card has an uppercase letter written on it. Toastman must choose k cards from Appleman's cards. Then Appleman should give Toastman some coins depending on the chosen cards. Formally, for each Toastman's card i you should calculate how much Toastman's cards have the letter equal to letter on ith, then sum up all these quantities, such a number of coins Appleman should give to Toastman.

Given the description of Appleman's cards. What is the maximum number of coins Toastman can get?

Input

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 105). The next line contains n uppercase letters without spaces — the i-th letter describes the i-th card of the Appleman.

Output

Print a single integer – the answer to the problem.

Examples

Input

15 10
DZFDFZDFDDDDDDF


Output

82


Input

6 4
YJSNPI


Output

4

Note

In the first test example Toastman can choose nine cards with letter D and one additional card with any letter. For each card with D he will get 9 coins and for the additional card he will get 1 coin.
#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
using str = string;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<double, double>;
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<double>;
using vs = vector<string>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
const int di[4] = {-1, 0, 1, 0}, dj[4] = {0, 1, 0, -1};
const int di8[8] = {-1, -1, 0, 1, 1, 1, 0, -1},
          dj8[8] = {0, 1, 1, 1, 0, -1, -1, -1};
const ld PI = acos((ld)-1);
const ll INF = 1e18;
const double eps = 1e-11;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll randint(ll a, ll b) { return uniform_int_distribution<ll>(a, b)(rng); }
using ul = unsigned long long;
ul modMul(ul a, ul b, const ul mod) {
  ll ret = a * b - mod * (ul)((ld)a * b / mod);
  return ret + ((ret < 0) - (ret >= (ll)mod)) * mod;
}
ul modPow(ul a, ul b, const ul mod) {
  if (b == 0) return 1;
  ul res = modPow(a, b / 2, mod);
  res = modMul(res, res, mod);
  return b & 1 ? modMul(res, a, mod) : res;
}
bool prime(ul n) {
  if (n < 2 || n % 6 % 4 != 1) return n - 2 < 2;
  ul A[] = {2, 325, 9375, 28178, 450775, 9780504, 1795265022},
     s = __builtin_ctzll(n - 1), d = n >> s;
  for (auto& a : A) {
    ul p = modPow(a, d, n), i = s;
    while (p != 1 && p != n - 1 && a % n && i--) p = modMul(p, p, n);
    if (p != n - 1 && i != s) return 0;
  }
  return 1;
}
template <typename A, typename B>
pair<A, B> operator+(const pair<A, B>& a, const pair<A, B>& b) {
  return make_pair(a.first + b.first, a.second + b.second);
}
template <typename A, typename B>
pair<A, B> operator+=(pair<A, B>& a, const pair<A, B>& b) {
  a.first += b.first;
  a.second += b.second;
  return a;
}
template <typename A, typename B>
pair<A, B> operator-(const pair<A, B>& a, const pair<A, B>& b) {
  return make_pair(a.first - b.first, a.second - b.second);
}
template <typename A, typename B>
pair<A, B> operator-(const pair<A, B>& a) {
  return make_pair(-a.first, -a.second);
}
template <typename A, typename B>
pair<A, B>& operator++(pair<A, B>& a) {
  ++a.first;
  ++a.second;
  return a;
}
template <typename A, typename B>
pair<A, B>& operator--(pair<A, B>& a) {
  --a.first;
  --a.second;
  return a;
}
template <typename A>
vector<A>& operator++(vector<A>& a) {
  for (auto it = a.begin(); it != a.end(); ++it) ++*it;
  return a;
}
template <typename A>
vector<A>& operator--(vector<A>& a) {
  for (auto it = a.begin(); it != a.end(); ++it) --*it;
  return a;
}
template <typename A, typename B>
pair<A, B> operator++(pair<A, B>& a, int) {
  pair<A, B> b = a;
  ++a;
  return b;
}
template <typename A, typename B>
pair<A, B> operator--(pair<A, B>& a, int) {
  pair<A, B> b = a;
  --a;
  return b;
}
template <typename A>
vector<A>& operator++(vector<A>& a, int) {
  vector<A> b = a;
  ++a;
  return b;
}
template <typename A>
vector<A>& operator--(vector<A>& a, int) {
  vector<A> b = a;
  --a;
  return b;
}
template <typename A, typename B>
pair<A, B> operator-=(pair<A, B>& a, const pair<A, B>& b) {
  a.first -= b.first;
  a.second -= b.second;
  return a;
}
bool pow2(int i) { return i && (i & -i) == i; }
constexpr int pct(int x) { return __builtin_popcount(x); }
constexpr int bits(int x) { return 31 - __builtin_clz(x); }
ll cdiv(ll a, ll b) { return a / b + ((a ^ b) > 0 && a % b); }
ll fdiv(ll a, ll b) { return a / b - ((a ^ b) < 0 && a % b); }
ll half(ll x) { return fdiv(x, 2); }
bool inc(ll a, ll b, ll c) { return a <= b && b <= c; }
template <class t>
int lwb(const vector<t>& v, const t& a) {
  return lower_bound((v).begin(), (v).end(), a) - v.begin();
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <typename I>
struct _reversed_struct {
  I& v_;
  explicit _reversed_struct(I& v) : v_{v} {}
  typename I::reverse_iterator begin() const { return v_.rbegin(); }
  typename I::reverse_iterator end() const { return v_.rend(); }
};
template <typename I>
_reversed_struct<I> reversed(I& v) {
  return _reversed_struct<I>(v);
}
template <typename T1, typename T2>
typename vector<pair<T1, T2>>::iterator lower_bound(
    const vector<pair<T1, T2>>& v, const T1& x) {
  return lower_bound(
      (v).begin(), (v).end(), x,
      [](pair<T1, T2> a, pair<T1, T2> b) { return a.first < b.first; });
}
template <typename T1, typename T2>
typename vector<pair<T1, T2>>::iterator upper_bound(
    const vector<pair<T1, T2>>& v, const T1& x) {
  return upper_bound(
      (v).begin(), (v).end(), x,
      [](pair<T1, T2> a, pair<T1, T2> b) { return a.first < b.first; });
}
bool isUpperCase(char c) { return c >= 'A' && c <= 'Z'; }
bool isLowerCase(char c) { return c >= 'a' && c <= 'z'; }
bool isLetter(char c) { return c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z'; }
bool isDigit(char c) { return c >= '0' && c <= '9'; }
char toLowerCase(char c) { return (isUpperCase(c)) ? (c + 32) : c; }
char toUpperCase(char c) { return (isLowerCase(c)) ? (c - 32) : c; }
int toInt(string s) {
  int r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
ll toInt64(string s) {
  ll r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
double toDouble(string s) {
  double r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
double dist(double x1, double y1, double x2, double y2) {
  return sqrt(sqr(x1 - x2) + sqr(y1 - y2));
}
double distR(double x1, double y1, double x2, double y2) {
  return sqr(x1 - x2) + sqr(y1 - y2);
}
template <class T>
T cross(T x0, T y0, T x1, T y1, T x2, T y2) {
  return (x1 - x0) * (y2 - y0) - (x2 - x0) * (y1 - y0);
}
int crossOper(double x0, double y0, double x1, double y1, double x2,
              double y2) {
  double t = (x1 - x0) * (y2 - y0) - (x2 - x0) * (y1 - y0);
  if (fabs(t) <= eps) return 0;
  return (t < 0) ? -1 : 1;
}
bool isIntersect(double x1, double y1, double x2, double y2, double x3,
                 double y3, double x4, double y4) {
  return crossOper(x1, y1, x2, y2, x3, y3) * crossOper(x1, y1, x2, y2, x4, y4) <
             0 &&
         crossOper(x3, y3, x4, y4, x1, y1) * crossOper(x3, y3, x4, y4, x2, y2) <
             0;
}
bool isMiddle(double s, double m, double t) {
  return fabs(s - m) <= eps || fabs(t - m) <= eps || (s < m) != (t < m);
}
constexpr ll power(ll x, int p) { return p == 0 ? 1 : (x * power(x, p - 1)); }
bool isPower(ll x, ll y) {
  ll res1 = log(y) / log(x);
  double res2 = log(y) / log(x);
  return (res1 == res2);
}
template <class T>
bool chmin(T& a, const T& b) {
  return b < a ? a = b, 1 : 0;
}
template <class T>
bool chmax(T& a, const T& b) {
  return a < b ? a = b, 1 : 0;
}
void TIME() {}
template <class T>
void remDup(vector<T>& v) {
  sort((v).begin(), (v).end());
  v.erase(unique((v).begin(), (v).end()), end(v));
}
template <class T, class U>
void remAll(vector<T>& v, U a) {
  v.erase(remove((v).begin(), (v).end(), a), v.end());
}
template <class T, class U>
T fstTrue(T lo, T hi, U f) {
  while (lo < hi) {
    T mid = half(lo + hi);
    f(mid) ? hi = mid : lo = mid + 1;
  }
  return lo;
}
template <class T, class U>
T lstTrue(T lo, T hi, U f) {
  while (lo < hi) {
    T mid = half(lo + hi + 1);
    f(mid) ? lo = mid : hi = mid - 1;
  }
  return lo;
}
template <class T, class U, class C>
string to_string(tuple<T, U, C> p);
template <class T, class U, class C, class D>
string to_string(tuple<T, U, C, D> p);
string to_string(char c) { return string(1, c); }
string to_string(bool b) { return to_string((int)b); }
string to_string(const char* s) { return (string)s; }
string to_string(string s) { return s; }
template <class T>
string to_string(complex<T> c) {
  stringstream ss;
  ss << c;
  return ss.str();
}
string to_string(vb v) {
  string res = "{";
  for (int i = (0); i < (((int)(v).size())); ++i) res += char('0' + v[i]);
  res += "}";
  return res;
}
template <size_t SZ>
string to_string(bitset<SZ> b) {
  string res = "";
  for (int i = (0); i < (((int)(b).size())); ++i) res += char('0' + b[i]);
  return res;
}
template <class T, class U>
string to_string(pair<T, U> p);
template <class T>
string to_string(T v) {
  bool fst = 1;
  string res = "";
  for (const auto& x : v) {
    if (!fst) res += " ";
    fst = 0;
    res += to_string(x);
  }
  return res;
}
template <class T, class U>
string to_string(pair<T, U> p) {
  return to_string(p.first) + " " + to_string(p.second);
}
template <class T, class U, class C>
string to_string(tuple<T, U, C> p) {
  return to_string(get<0>(p)) + " " + to_string(get<1>(p)) + " " +
         to_string(get<2>(p));
}
template <class T, class U, class C, class D>
string to_string(tuple<T, U, C, D> p) {
  return to_string(get<0>(p)) + " " + to_string(get<1>(p)) + " " +
         to_string(get<2>(p)) + " " + to_string(get<3>(p));
}
template <class T, class U, class C>
void re(tuple<T, U, C>& p);
template <class T, class U, class C, class D>
void re(tuple<T, U, C, D>& p);
template <class T>
void re(complex<T>& c);
template <class T, class U>
void re(pair<T, U>& p);
template <class T>
void re(vector<T>& v);
template <class T>
void rv(int n, vector<T>& x) {
  x.resize(n);
  re(x);
}
template <class T, size_t SZ>
void re(array<T, SZ>& a);
template <class T>
void re(T& x) {
  cin >> x;
}
void re(double& d) {
  string t;
  re(t);
  d = stod(t);
}
void re(ld& d) {
  string t;
  re(t);
  d = stold(t);
}
template <class T, class... U>
void re(T& t, U&... u) {
  re(t);
  re(u...);
}
template <class T>
void re(complex<T>& c) {
  T a, b;
  re(a, b);
  c = {a, b};
}
template <class T, class U>
void re(pair<T, U>& p) {
  re(p.first, p.second);
}
template <class T>
void re(vector<T>& x) {
  for (auto& a : x) re(a);
}
template <class T, size_t SZ>
void re(array<T, SZ>& x) {
  for (auto& a : x) re(a);
}
template <class T, class U, class C>
void re(tuple<T, U, C>& p) {
  re(get<0>(p), get<1>(p), get<2>(p));
}
template <class T, class U, class C, class D>
void re(tuple<T, U, C, D>& p) {
  re(get<0>(p), get<1>(p), get<2>(p), get<3>(p));
}
template <class T>
void pr(T x) {
  cout << to_string(x);
}
template <class T, class... U>
void pr(const T& t, const U&... u) {
  pr(t);
  pr(u...);
}
void ps() { pr("\n"); }
template <class T, class... U>
void ps(const T& t, const U&... u) {
  pr(t);
  if (sizeof...(u)) pr(" ");
  ps(u...);
}
struct chash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
  template <typename L, typename R>
  size_t operator()(pair<L, R> const& second) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(second.first * 31 + second.second + FIXED_RANDOM);
  }
};
template <class T>
using V = vector<T>;
template <class T, size_t SZ>
using AR = array<T, SZ>;
template <class T>
using mpq = priority_queue<T, vector<T>, greater<T>>;
template <class T>
using pq = priority_queue<T>;
template <class T, class U>
using um = unordered_map<T, U, chash>;
template <class T>
using us = unordered_set<T, chash>;
template <class T>
using PR = pair<T, T>;
const int MOD = 998244353;
template <int MOD, int RT>
struct mint {
  static const int mod = MOD;
  static constexpr mint rt() { return RT; }
  int v;
  explicit operator int() const { return v; }
  mint() { v = 0; }
  mint(ll _v) {
    v = (-MOD < _v && _v < MOD) ? _v : _v % MOD;
    if (v < 0) v += MOD;
  }
  friend bool operator==(const mint& a, const mint& b) { return a.v == b.v; }
  friend bool operator!=(const mint& a, const mint& b) { return !(a == b); }
  friend bool operator<(const mint& a, const mint& b) { return a.v < b.v; }
  friend void re(mint& a) {
    ll x;
    re(x);
    a = mint(x);
  }
  friend string to_string(mint a) { return to_string(a.v); }
  mint& operator+=(const mint& m) {
    if ((v += m.v) >= MOD) v -= MOD;
    return *this;
  }
  mint& operator-=(const mint& m) {
    if ((v -= m.v) < 0) v += MOD;
    return *this;
  }
  mint& operator*=(const mint& m) {
    v = (ll)v * m.v % MOD;
    return *this;
  }
  mint& operator/=(const mint& m) { return (*this) *= inv(m); }
  friend mint pow(mint a, ll p) {
    mint ans = 1;
    assert(p >= 0);
    for (; p; p /= 2, a *= a)
      if (p & 1) ans *= a;
    return ans;
  }
  friend mint inv(const mint& a) {
    assert(a.v != 0);
    return pow(a, MOD - 2);
  }
  mint operator-() const { return mint(-v); }
  mint& operator++() { return *this += 1; }
  mint& operator--() { return *this -= 1; }
  friend mint operator+(mint a, const mint& b) { return a += b; }
  friend mint operator-(mint a, const mint& b) { return a -= b; }
  friend mint operator*(mint a, const mint& b) { return a *= b; }
  friend mint operator/(mint a, const mint& b) { return a /= b; }
};
typedef mint<MOD, 5> mi;
vector<vector<mi>> scmb;
void genComb(int SZ) {
  scmb.assign(SZ, vector<mi>(SZ));
  scmb[0][0] = 1;
  for (int i = (1); i < (SZ); ++i)
    for (int j = (0); j < (i + 1); ++j)
      scmb[i][j] = scmb[i - 1][j] + (j ? scmb[i - 1][j - 1] : 0);
}
vi invs, fac, ifac;
void genFac(int SZ) {
  invs.resize(SZ), fac.resize(SZ), ifac.resize(SZ);
  invs[1] = fac[0] = ifac[0] = 1;
  for (int i = (2); i < (SZ); ++i)
    invs[i] = MOD - (ll)MOD / i * invs[MOD % i] % MOD;
  for (int i = (1); i < (SZ); ++i) {
    fac[i] = (ll)fac[i - 1] * i % MOD;
    ifac[i] = (ll)ifac[i - 1] * invs[i] % MOD;
  }
}
mi comb(int a, int b) {
  if (a < b || b < 0) return 0;
  return (ll)fac[a] * ifac[b] % MOD * ifac[a - b] % MOD;
}
ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; }
ll ncr(ll n, ll r) {
  ll p = 1, k = 1;
  if (n - r < r) r = n - r;
  if (r != 0) {
    while (r) {
      p *= n;
      k *= r;
      ll m = gcd(p, k);
      p /= m;
      k /= m;
      n--;
      r--;
    }
  } else
    p = 1;
  return p;
}
void DBG() { cerr << "]" << endl; }
template <class T, class... U>
void DBG(const T& t, const U&... u) {
  cerr << to_string(t);
  if (sizeof...(u)) cerr << ", ";
  DBG(u...);
}
V<vi> readGraph(int n, int m) {
  V<vi> g(n);
  for (int i = (0); i < (m); ++i) {
    int a, b;
    re(a, b);
    a--;
    b--;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  return g;
}
V<vpi> readwGraph(int n, int m) {
  V<vpi> g(n);
  for (int i = (0); i < (m); ++i) {
    int a, b, w;
    re(a, b, w);
    a--;
    b--;
    g[a].emplace_back(b, w);
    g[b].emplace_back(a, w);
  }
  return g;
}
V<vi> readTree(int n) { return readGraph(n, n - 1); }
V<vpi> readwTree(int n) { return readwGraph(n, n - 1); }
void setPrec() { cout << fixed << setprecision(15); }
void setIn(str s) { freopen(s.c_str(), "r", stdin); }
void setOut(str s) { freopen(s.c_str(), "w", stdout); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
void setIO(str s = "") {
  unsyncIO();
  setPrec();
  if (((int)(s).size())) {
    setIn(s + ".in");
    setOut(s + ".out");
  }
}
const int mxN = 5e4 + 5;
void solve() {
  ll n, k, x = 0;
  str s;
  re(n, k, s);
  vl c(26);
  for (auto& i : s) c[i - 'A']++;
  sort((c).rbegin(), (c).rend());
  for (int i = (0); i < (26); ++i) {
    ll d = min(k, c[i]);
    k -= d;
    x += d * d;
  }
  ps(x);
}
int main() {
  setIO();
  int T = 1;
  for (int _ = (1); _ < (T + 1); ++_) {
    solve();
  }
}
