# include<iostream>

# include<cstdio>

# include<cstring>

# include<vector>

# include<queue>

# include<algorithm>

using namespace std;

const int INF=1<<30;

struct Edge

{

    int to,w,nxt;

};

Edge G[35000];

int a[5][105],n,t;

int v[5],head[505],cnt;

int d[505];

bool read(int &val)

{

    val=0;

    char c;

    while(c=getchar()){

        if(c=='\n') return false;

        else if(c==' ') return true;

        else val=val*10+c-'0';

    }

}

void addEdge(int fr,int to,int w)

{

    G[cnt].to=to;

    G[cnt].w=w;

    G[cnt].nxt=head[fr];

    head[fr]=cnt++;

    G[cnt].to=fr;

    G[cnt].w=w;

    G[cnt].nxt=head[to];

    head[to]=cnt++;

}

int spfa()

{

    fill(d,d+500,INF);

    queue<int>q;

    for(int i=0;i<500;i+=100){

        d[i]=0;

        q.push(i);

    }

    while(!q.empty()){

        int u=q.front();

        q.pop();

        for(int i=head[u];i!=-1;i=G[i].nxt){

            int nu=G[i].to;

            if(d[nu]>d[u]+G[i].w){

                d[nu]=d[u]+G[i].w;

                q.push(nu);

            }

        }

    }

    int res=INF;

    for(int i=0;i<500;i+=100)

        res=min(res,d[t+i]);

    return res;

}

int main()

{

    while(~scanf("%d%d",&n,&t))

    {

        for(int i=0;i<n;++i) scanf("%d",v+i);

        cnt=0;

        memset(head,-1,sizeof(head));

        getchar();

        for(int i=0;i<n;++i){

            a[i][0]=0;

            int val;

            while(read(val))

            {

                a[i][++a[i][0]]=val;

            }

            a[i][++a[i][0]]=val;

        }

        for(int i=0;i<n;++i)

            for(int j=1;j<=a[i][0];++j)

                for(int k=j+1;k<=a[i][0];++k)

                    addEdge(i*100+a[i][j],i*100+a[i][k],(a[i][k]-a[i][j])*v[i]);

        for(int i=0;i<100;++i)

            for(int j=0;j<500;j+=100)

                for(int k=j+100;k<500;k+=100)

                    addEdge(i+j,i+k,60);

        int ans=spfa();

        if(ans==INF)

            printf("IMPOSSIBLE\n");

        else printf("%d\n",ans);

    }

    return 0;

}