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#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <set>
#include <map>
#include <cmath>
#include <list>
#include <ctime>
#include <sstream>
#include <queue>
#include <stack>
#include <bitset>
#include <unordered_set>
#include <unordered_map>
using namespace std;
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;
typedef short int sint;
#define FOR(x, b, e) for(int x=(b); x<=(e); ++x)
#define FORD(x, b, e) for(int x=((int)(b))-1; x>=(e); --x)
#define REP(x, n) for(int x=0; x<(n); ++x)
#define ALL(c) c.begin(),c.end()
#define SIZE(x) ((int)((x).size()))
#define PB push_back
#define ST first
#define ND second
#define DEBUG 0
#define debug(x) {if (DEBUG)cerr <<#x <<" = " <<x <<endl; }
#define debugv(x) {if (DEBUG) {cerr <<#x <<" = "; FOREACH(it, (x)) cerr <<*it <<", "; cout <<endl; }}
#define REMAX(a,b) (a)=max((a),(b));
#define REMIN(a,b) (a)=min((a),(b));
#define wez(n) int (n); scanf("%d",&(n));
#define wez2(n,m) int (n),(m); scanf("%d %d",&(n),&(m));

const ll inf = 3e18;
const int N = 200;
const int K = 60;
const int M = 2;
ll tab[M][M][K][N][N];
bool cnt[M][M][K][N][N];
int mRozklad[K];
int n;
ll m;
ll a[N], s[N];

inline ll sum(int x, int y) {
	ll res = s[y];
	if (x > 0) {
		res -= s[x - 1];
	}
	return res;
}

ll f(bool isMax, bool isNonZero, int pos, int x, int y) {
	if (DEBUG)printf("\tf(%d, %d, %d, %d, %d)\n", isMax, isNonZero, pos, x, y);
	if (pos == K) {
		if (x == y && (isNonZero || x == 0)) {
			return 0;
		} else {
			return -inf;
		}
		// if (DEBUG)printf("6f(%d, %d, %d, %d, %d) - %lld\n", isMax, isNonZero, pos, x, y, res);
		// return res;
	}
	ll &res = tab[isMax][isNonZero][pos][x][y];
	if (cnt[isMax][isNonZero][pos][x][y]) {
		if (DEBUG)printf("7f(%d, %d, %d, %d, %d) - %lld\n", isMax, isNonZero, pos, x, y, res);
		return tab[isMax][isNonZero][pos][x][y];
	}
	cnt[isMax][isNonZero][pos][x][y] = true;
	
	int d = (y - x + 1);
	int bitZost = K - pos;
	ll dl = (1LL << bitZost);
	if (DEBUG)printf("d: %d, dl: %lld\n", d, dl);
	if (isMax && mRozklad[pos] == 0) {
		res = f(true, isNonZero, pos + 1, x, y);
		if (DEBUG)printf("4f(%d, %d, %d, %d, %d) - %lld\n", isMax, isNonZero, pos, x, y, res);
		return res;
	} else if (d > dl) {
		res = -inf;
		if (DEBUG)printf("3f(%d, %d, %d, %d, %d) - %lld\n", isMax, isNonZero, pos, x, y, res);
		return res;
	} else if (isMax && mRozklad[pos] == 0) {
		res = f(true, isNonZero, pos + 1, x, y);
		if (DEBUG)printf("4f(%d, %d, %d, %d, %d) - %lld\n", isMax, isNonZero, pos, x, y, res);
		return res;
	} else {
		// same 0
		int bestD = 0;
		res = -inf;
		res = max(res, f(false, isNonZero, pos + 1, x, y));
		FOR(i, 1, d - 1) {
			// i <- oznacza ile zer
			// d - i
			ll temp = sum(x + i, y) + f(isMax, true, pos + 1, x + i, y) + f(false, isNonZero, pos + 1, x, x + i - 1);
			if (temp > res) {
				res = temp;
				bestD = d - i;
			}
		}
		// same 1
		ll temp = sum(x, y) + f(isMax, true, pos + 1, x, y);
		if (temp > res) {
			res = temp;
			bestD = d;
		}
		if (DEBUG)printf("5f(%d, %d, %d, %d, %d) - %lld, with %d ones\n", isMax, isNonZero, pos, x, y, res, bestD);
		return res;
	}
}

int main() {
	cin >> n >> m;
	REP(i, n) {
		cin >> a[i];
	}
	s[0] = a[0];
	FOR(i, 1, n - 1) {
		s[i] = s[i - 1] + a[i];
	}
	int fPos = -1;
	REP(i, K) {
		int wyk = K - i - 1;
		if (m & (1LL << wyk)) {
			if (fPos == -1) fPos = i;
			mRozklad[i] = 1;
		} else {
			mRozklad[i] = 0;
		}
	}
	ll res = f(true, false, fPos, 0, n - 1);
	cout << res << endl;
	return 0;
}