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#include <cstdio>
#include <algorithm>

#define REP(a, n) for (int a = 0; a < (n); ++a)
#define FOR(a, b, c) for (int a = (b); a <= (c); ++a)

          //  123456789012345678
#define INF (1300000000000000000LL)

typedef long long LL;

using namespace std;

//////////////////////

LL tab[200], suma[201], best[201][201][64], last[201][64];
int N;
LL M;

inline int wszystkie(int b) {
    return min(N + 1LL, 1LL << b);
}

inline int to_last_bits(int b) {
    return min(N + 1LL, (M & ((1LL << b) - 1)) + 1);
}

int main() {
    scanf("%d%lld", &N, &M);
    REP(a, N) {
        scanf("%lld", &tab[a]);
        suma[a + 1] = suma[a] + tab[a];
    }
    FOR(b, 1, 61)
        REP(i, N) {
            FOR(k, i + 1, min(N, i + wszystkie(b))) {
                best[i][k][b] = -INF;
                int beg = max(k - wszystkie(b - 1), i);
                int end = min(i + wszystkie(b - 1), k);
                FOR(j, beg, end)
                    best[i][k][b] = max(best[i][k][b], best[i][j][b - 1] + best[j][k][b - 1] + suma[k] - suma[j]);
            }
            if (M & (1LL << (b - 1))) {
                last[i][b] = -INF;
                int beg = max(N - to_last_bits(b - 1), i);
                int end = min(i + wszystkie(b - 1), N);
                FOR(j, beg, end)
                    last[i][b] = max(last[i][b], best[i][j][b - 1] + last[j][b - 1] + suma[N] - suma[j]);
            }
            else
                last[i][b] = last[i][b - 1];
        }
    printf("%lld\n", last[0][61]);
}