#include <bits/stdc++.h>
using namespace std;

long long dp[3001][3001];

int main() {
    int N, M; cin >> N >> M;
    vector<int> A(N);
    for(int i = 0; i < N; i++) {
        cin >> A[i];
    }
    sort(A.begin(), A.end());
    
    for(int i = 1; i <= N; i++) {
        for(int j = 0; j <= M; j++) {
            dp[i][j] = dp[i - 1][j];
            if(j) dp[i][j] = max(dp[i][j], dp[i][j - 1]);
            if(i >= 2 && A[i - 1] - A[i - 2] <= j)
                dp[i][j] = max(dp[i][j], A[i - 1] + dp[i - 2][j - (A[i - 1] - A[i - 2])]);
        }
    }
    cout << dp[N][M] << "\n";
}