1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <cmath>
  5 #include <queue>
  6 using namespace std;
  7 
  8 const int maxn=205;
  9 const double eps=1e-8;
 10 int map[maxn],flag[maxn];
 11 double p[maxn],A[maxn][maxn];
 12 int cnt,n,m,st,ed,d;
 13 int dcmp(double x)
 14 {
 15     if(fabs(x)<eps) return 0;
 16     else if(x-0>eps) return 1;
 17     return -1;
 18 }
 19 void swap(double &a,double &b){double t=a;a=b;b=t;}
 20 
 21 bool bfs()
 22 {
 23     memset(flag,-1,sizeof(flag));
 24     queue<int>Q;
 25     cnt=0;flag[st]=cnt++;
 26     Q.push(st);
 27     bool ret=false;
 28     while(!Q.empty())
 29     {
 30         int u=Q.front();Q.pop();
 31         for(int i=1;i<=m;i++)
 32         {
 33             int v=(u+i)%(2*n-2);
 34             if(dcmp(p[i])==0) continue;
 35             if(flag[v]!=-1) continue;
 36             flag[v]=cnt++;
 37             if(map[v]==ed) ret=true;
 38             Q.push(v);
 39         }
 40     }
 41     return ret;
 42 }
 43 
 44 void bulidmatrix()
 45 {
 46     memset(A,0,sizeof(A));
 47     for(int i=0;i<2*n-2;i++)
 48     {
 49         if(flag[i]==-1) continue;
 50         int u=flag[i];A[u][u]=1;
 51         if(map[i]==ed){A[u][cnt]=0;continue;}
 52         for(int j=1;j<=m;j++)
 53         {
 54             int v=(i+j)%(2*n-2);
 55             if(flag[v]==-1) continue;
 56             v=flag[v];
 57             A[u][v]-=p[j];A[u][cnt]+=p[j]*j;
 58         }
 59     }
 60 }
 61 
 62 void gauss(int n)
 63 {
 64     int i,j,k,r;
 65     for(i=0;i<n;i++)
 66     {
 67         r=i;
 68         for(j=i+1;j<n;j++)
 69             if(fabs(A[j][i])>fabs(A[r][i])) r=j;
 70         if(dcmp(A[r][i])==0) continue;
 71         if(r!=i) for(j=0;j<=n;j++) swap(A[r][j],A[i][j]);
 72         for(k=0;k<n;k++) if(k!=i)
 73             for(j=n;j>=i;j--) A[k][j]-=A[k][i]/A[i][i]*A[i][j];
 74     }
 75 }
 76 
 77 int main()
 78 {
 79     int i,j,t;
 80     scanf("%d",&t);
 81     while(t--)
 82     {
 83         scanf("%d%d%d%d%d",&n,&m,&ed,&st,&d);
 84         for(i=1;i<=m;i++){ scanf("%lf",p+i);p[i]/=100;}
 85         if(st==ed){ printf("0.00\n");continue;}
 86         for(i=0;i<n;i++) map[i]=i;
 87         for(i=n,j=n-2;i<2*n-2;i++,j--) map[i]=j;
 88         if(d==1) st=2*n-2-st;
 89         if(!bfs()){ printf("Impossible !\n");continue;}
 90         bulidmatrix();gauss(cnt);
 91         for(i=cnt-1;i>=0;i--)
 92         {
 93             for(j=i+1;j<cnt;j++)
 94                 A[i][cnt]-=A[j][cnt]*A[i][j];
 95             A[i][cnt]/=A[i][i];
 96         }
 97         printf("%.2lf\n",A[0][cnt]);
 98     }
 99     return 0;
100 }