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

long long dp[207][207][60];
bool obl_dp[207][207][60];
long long dp2[207][207][60];
bool obl_dp2[207][207][60];
long long tab[207];

int policz(long long m) {
    return 63 - __builtin_clzll(m);
}

bool kk(int a, int b, long long m) {
    return b - a + 1 <= m;
}

long long rozp(int a, int b, long long m) {
    if (b < a || m == 1)
        return 0LL;
    int bit = policz(m);
    long long war = 1LL << bit;
    long long drugi;
    bool pot = war == m;
    if (!pot) {
        drugi = m - war;
        if (obl_dp2[a][b][bit])
            return dp2[a][b][bit];
    } else {
        drugi = war = war / 2;
        if (obl_dp[a][b][bit])
            return dp[a][b][bit];
    }
    long long wyn = LLONG_MIN;
    for (int sr = a; sr <= b + 1; sr++)
        if (kk(a, sr - 1, war) && kk(sr, b, m - war))
            wyn = max(wyn, rozp(a, sr - 1, war) + tab[b] - tab[sr - 1] + rozp(sr, b, drugi));
    if (!pot) {
        obl_dp2[a][b][bit] = true;
        return dp2[a][b][bit] = wyn;
    } else {
        obl_dp[a][b][bit] = true;
        return dp[a][b][bit] = wyn;
    }
}

int main() {
    int N;
    long long M;
    scanf("%d%lld", &N, &M);
    for (int i = 1; i <= N; i++) {
        scanf("%lld", &tab[i]);
        tab[i] += tab[i - 1];
    }
    printf("%lld\n", rozp(1, N, M + 1));
    return 0;
}