#include<iostream>

 #include<stdio.h>

 #include<algorithm>

 #include<iomanip>

 #include<cmath>

 #include<cstring>

 #include<vector>

 #define ll __int64

 #define pi acos(-1.0)

 #define MAX 50002

 using namespace std;

 double a[MAX][],p[MAX][],consts[MAX],q;

 int c[MAX],cc,l[MAX],r[MAX];

 int main(){

     int n,m,i,j,k;

     while(scanf("%d%d",&n,&m)&&(n+m)){

         memset(a,,sizeof(a));

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

             cc=;

             for(j=;j<=m;j++){

                 scanf("%d",&c[j]);

                 cc+=c[j];

             }

             p[i][m]=1.0;

             for(j=-m;j<;j++){

                 p[i][j+m]=0.3*c[-j]/cc;

                 if(i+j>=) p[i][m]-=p[i][j+m];

             }

             for(j=;j<=m;j++){

                 p[i][j+m]=0.7*c[j]/cc;

                 if(i+j<=n) p[i][m]-=p[i][j+m];

             }

         }

         for(i=n-;i>=;i--){

             l[i]=max(,i-m);//记录该方程的下界

             r[i]=min(n,i+m);//记录该方程的上界

             for(j=;j<r[i]-l[i]+;j++)

                 a[i][j]=p[i][l[i]+j-i+m];

             consts[i]=1.0;//记录常数

             for(j=r[i];j>i;j--){//将比i高位的变量消去

                 if(j==n) a[i][j-l[i]]=;//dp[n]=0

                 else{

                     q=a[i][j-l[i]];

                     if(fabs(q)<1e-) continue;//从i到j的概率为0，不需计算

                     for(k=;k<j-l[j];k++)//将相应变量的系数相加

                         a[i][k+l[j]-l[i]]+=a[j][k]*q;

                     consts[i]+=consts[j]*q;//将常数项相加

                 }

             }

             q=1.0-a[i][i-l[i]];

             for(j=;j<r[i]-l[i]+;j++)

                 a[i][j]/=q;

             a[i][i-l[i]]=;

             consts[i]/=q;

         }

         printf("%.2lf\n",consts[]);

     }

     return ;

 }