#include <fstream>
#include <vector>
#include <algorithm>
#include <cstring>

using namespace std;

ifstream fin("euro.in");
ofstream fout("euro.out");

const int dim = 40005;

long long n, t;
long long a[dim], dp[dim];

vector< pair<long long, int> > v;

int main() {

	fin >> n >> t;
	
	long long sum = 0;
	for (int i = 1; i <= n; ++i) {

		fin >> a[i];
		sum += a[i];

		if (sum < 0) {

			v.push_back(make_pair(sum, i));
			sum = 0;

		}

	}

	if (!v.size() || v[v.size() - 1].second != n)
		v.push_back(make_pair(sum, (int)n));

	for (int i = 0; i < (int)v.size(); ++i) {

		sum = v[i].first;
		int day = v[i].second;

		dp[i + 1] = dp[i] + sum * day - t;

		for (int j = i - 1; j >= 0 && 1LL * (i - j)*(i - j) <= t + 1; --j) {

			sum += v[j].first;
			dp[i + 1] = max(dp[i + 1], dp[j] + sum * day - t);

		}

	}

	fout << dp[v.size()] << '\n';

	return 0;

}

//Trust me, I'm the Doctor!