#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

int main() {
    cin.tie(0);
	ios::sync_with_stdio(false);

	int N, K;
	cin >> N >> K;

	vector<vector<int>> v(10);
	FOR(i, 0, N) {
	    int C, G;
	    cin >> C >> G;
	    G--;
	    v[G].emplace_back(C);
	}

	map<int, vector<vector<int>>> memo;
	FOR(kind, 0, 10) {
        vector<vector<int>> dp(v[kind].size() + 1, vector<int>(N + 1, -INF));
	    dp[0][0] = 0;
        FOR(i, 0, v[kind].size()) {
            FOR(j, 0, N) {
                int price = v[kind][i];
                if (dp[i][j] == -INF) {
                    continue;
                }

                // not use
                dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);

                // use
                dp[i + 1][j + 1] = max(dp[i + 1][j + 1], dp[i][j] + price);
            }
        }
        memo[kind] = dp;
    }

    vector<vector<int>> dp2(11, vector<int>(N + 1, -INF));
	dp2[0][0] = 0;

	FOR(kind, 0, 10) {
        FOR(i, 0, dp2[0].size()) {
            if (dp2[kind][i] == -INF) {
                continue;
            }
            int num = v[kind].size();
            FOR(j, 0, num + 1) {
                int price = memo[kind][num][j] + max(0, j - 1) * j;
                // use
                dp2[kind + 1][i + j] = max(dp2[kind + 1][i + j], dp2[kind][i] + price);
            }
        }
    }

    int ans = 0;
    FOR(i, 0, K + 1) {
        ans = max(ans, dp2[10][i]);
    }
    print(ans);

	return 0;
}


Measured memory_bytes: 32996