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#include <bits/stdc++.h>
using namespace std;
#define FOR(i,x,y) for(int i=(int)(x);i<(int)(y);++i)
#define FORE(i,x,y) for(int i=(int)(x);i<=(int)(y);++i)
#define FORD(i,x,y) for(int i=(int)(x);i>=(int)(y);--i)
#define PB push_back
#define MP make_pair
#define ST first
#define ND second
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> p2ll;
const int MAXN=2e2+6;

ll sum=0;
ll n,m;
ll a[MAXN];
map<ll,ll> mp[2];
ll bt;
ll prv1(ll v,ll d){
    /*ll res=(1LL<<v);
    --res;
    ll pos=62;
    --v;
    while(pos>v&&v>=0){
        ll tr=((res|(1LL<<pos))&(~(1LL<<v)));
        if(tr<=d){
            res=tr;
            --v;
        }
        --pos;
    }
    return res;*/
    ll res=d;
    if(bt<v){
        ll i=0;
        while(bt<v){
            if(!(d&1)){
                res|=(1LL<<i);
                --v;
            }
            ++i;
            d/=2;
        }
        while((d&1))d/=2,++i;
        if(d==0)return res;
        while(!(d&1)){
            ++i;
            d/=2;
        }
        res|=(1LL<<(i-1));
        res&=(~(1LL<<(i)));
    }else if(bt>v){
        ll i=0;
        while(bt>v){
            if(d&1){
                res&=(~(1LL<<i));
                ++v;
            }
            ++i;
            d/=2;
        }
    }
    return res;
}
ll lg2(ll v){
    ll res=-1;
    while(v>0)v/=2,++res;
    return res;
}
ll Bts(ll v){
    ll res=0;
    while(v>0){
        if(v&1)++res;
        v/=2;
    }
    return res;
}
int main()
{
    ios_base::sync_with_stdio(false);cin.tie(0);
    cin>>n>>m;
    FOR(i,0,n)cin>>a[i];

    int sile;
    if(n>70)sile=35;
    if(n>80)sile=30;
    if(n>90)sile=25;
    if(n>100)sile=20;
    if(n>120)sile=15;
    if(n>150)sile=10;
    if(n>170)sile=8;



    int t=0,p=1;
    mp[p].insert(MP(0,m+1));
    FORD(i,n-1,0){
        mp[t].clear();
        map<ll,ll>::iterator it,it2;
        it=mp[p].end();
        --it;
        int cos=0;
        for(;true;--it){
			++cos;
            ll c=it->ST;
            ll d=it->ND;
            ll x=lg2(d);
            c+=a[i]*x;
            bt=Bts(d-1);
            int ile=sile;
            if(a[i]<=0)ile=100;
            for(;x>=0;--x){
                --ile;
                ll pos=prv1(x,d-1);
                if(pos>d)continue;
                it2=mp[t].lower_bound(c);
                if(it2==mp[t].end()){
                    mp[t].insert(it2,MP(c,pos));
                    --it2;
                }else if(it2->ND<pos){
                    if(it2->ST==c){
                        it2->ND=pos;
                    }else{
                        mp[t].insert(it2,MP(c,pos));
                        --it2;
                    }
                }
                if(it2!=mp[t].begin()){
                    --it2;
                    while(true){
                        if(it2->ND<=pos){
                            it2=mp[t].erase(it2);
                        }else{
                            break;
                        }
                        if(it2==mp[t].begin())break;
                        --it2;
                    }

                }
                c-=a[i];
                if(ile<0||cos>10000)break;
            }
            if(it==mp[p].begin())break;
        }
        swap(t,p);
    }
    map<ll,ll>::iterator it=mp[p].end();
    --it;
    cout<<it->ST<<"\n";
    return 0;
}