# include <cstdio>

const char *FIN = "euro.in", *FOU = "euro.out";
const int MAX = 34569;

int N, T, V[MAX], S[MAX];

struct vec {
    int x, y;
    vec () {} ;
    vec (int a, int b) {
        x = a, y = b;
    };
} ;
vec A[MAX];
long long dp[MAX];

inline void getmax (long long &A, long long B) {
    A = A > B ? A : B;
}

int main (void) {
    freopen (FIN, "r", stdin);

    scanf ("%d %d", &N, &T);
    for (int i = 1; i <= N; ++i) {
        scanf ("%d", V + i);
        S[i] = S[i - 1] + V[i];
        if (A[A[0].x].x < 0 || A[0].x == 0) ++A[0].x;
        A[A[0].x] = vec (A[A[0].x].x + V[i], i);
    }
    for (int i = 1; i <= A[0].x; ++i) {
        dp[i] = -0x3f3f3f3f3f3f3fLL;
        for (int j = i; j + 1 && (i - j) * (i - j) <= 1000 + T; --j)
            getmax (dp[i], dp[j] + (S[A[i].y] - S[A[j].y]) * 1LL * A[i].y - T);
    }
    fprintf (fopen (FOU, "w"), "%lld", dp[A[0].x]);
}