#include <cstdio>
#include <vector>
#include <iostream>
using namespace std;
const int M = 605,NV=300;
#define int long long
const int inf = 1e18;
#define pb push_back
int read()
{
	int x=0,f=1;char c;
	while((c=getchar())<'0' || c>'9') {if(c=='-') f=-1;}
	while(c>='0' && c<='9') {x=(x<<3)+(x<<1)+(c^48);c=getchar();}
	return x*f;
}
int n,m,a[M],dp[2][2*NV*NV+5];vector<int> v[M];
signed main()
{
    n=read();m=read();
    for(int i=0;i<=(n<<1);i++)
    {
        a[i]=read();
        if(i==n) continue;
        for(int j=0;j<=40;j++) if((1ll<<j)<=a[i])
            v[j].pb(i-n),a[i]-=(1ll<<j);
        for(int j=40;j>=0;j--) if((1ll<<j)<=a[i])
            v[j].pb(i-n),a[i]-=(1ll<<j);
    }
    int e=0,t=1,L=NV*NV,R=NV*NV;dp[0][NV*NV]=inf;
    //都增加inf，这样0就相当于-inf
    for(int i=0;i<=40;i++)
    {
        for(int d:v[i])
        {
            e^=1;t^=1;
            int tl=min(L,max(0ll,L+d));
            int tr=max(R,min(2*NV*NV,R+d));
            for(int j=L;j<=R;j++) dp[e][j]=dp[t][j];
            for(int j=tl;j<L;j++) dp[e][j]=0;
            for(int j=R+1;j<=tr;j++) dp[e][j]=0;
            for(int j=L,k;j<=R;j++) if((k=j+d)>=0 && k<=2*NV*NV)
                dp[e][k]=max(dp[e][k],dp[t][j]+(1ll<<i));
            L=tl;R=tr;
        }
        e^=1;t^=1;
        for(int j=L;j<=R;j++) dp[e][j]=0;
        int tl=NV*NV,tr=NV*NV;
        for(int j=L,k;j<=R;j++) if((j&1)==(m>>i&1))
        {
            k=NV*NV+(j-NV*NV>>1);
            dp[e][k]=max(dp[e][k],dp[t][j]);
            tl=min(tl,k);tr=max(tr,k);
        }
        L=tl;R=tr;
    }
    if((m>>41)+NV*NV<L || (m>>41)+NV*NV>R || dp[e][(m>>41)+NV*NV]<inf)
        {puts("impossible");return 0;}
    printf("%lld\n",dp[e][(m>>41)+NV*NV]-inf+a[n]);
}

answer.code: In function ‘int main()’:
answer.code:37:29: error: no matching function for call to ‘min(int, long long int)’
   37 |             int tr=max(R,min(2*NV*NV,R+d));
      |                          ~~~^~~~~~~~~~~~~
In file included from /usr/include/c++/13/vector:62,
                 from answer.code:2:
/usr/include/c++/13/bits/stl_algobase.h:233:5: note: candidate: ‘template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)’
  233 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:233:5: note:   template argument deduction/substitution failed:
answer.code:37:29: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘long long int’)
   37 |             int tr=max(R,min(2*NV*NV,R+d));
      |                          ~~~^~~~~~~~~~~~~
/usr/include/c++/13/bits/stl_algobase.h:281:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)’
  281 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/13/bits/stl_algobase.h:281:5: note:   template argument deduction/substitution failed:
answer.code:37:29: note:   deduced conflicting types for parameter ‘const _Tp’ (‘int’ and ‘long long int’)
   37 |             int tr=max(R,min(2*NV*NV,R+d));
      |                          ~~~^~~~~~~~~~~~~