#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>
using namespace std;
const int N = 1050;
double map[N][N];
int n,m;
int getint()
{
    int res=0;
    char ch=getchar();
    while((ch<'0' || ch>'9') && ch!='-')
        ch=getchar();
    bool fan=0;
    if(ch=='-')
    {
        fan=1;
        ch=getchar();
    }
    while('0'<=ch && ch<='9')
    {
        res=res*10+ch-'0';
        ch=getchar();
    }
    if(fan)
        res=-res;
    return res;
}
void f()
{
    int i,j;
    m=getint();
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;j++)
            map[i][j]=getint();
    }
    double ans=0.0;
    for(i=1;i<=n;i++)
    {
        double now=0.0;
        for(j=1;j<=m;j++)
            now+=map[i][j];
        for(j=1;j<=m;j++)
        {
            double t=map[i][j]/now;
            map[i][j]=t;
            ans+=t*(1.0-t);
        }
    }
    for(j=1;j<=m;j++)
    {
        double now=0.0;
        for(i=1;i<=n;i++)
            now+=map[i][j];
        ans+=now*now;
    }
    printf("%.2f\n",ans);
}
int main()
{
    while(scanf("%d",&n)!=EOF)
        f();
    return 0;
}