#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <map>
#include <set>
#include <deque>
#include <cstring>
#include <functional>
#include <climits>
#include <list>
#include <ctime>
#include <complex>
 
#define F1(x,y,z) for(int x=y;x<z;x++)
#define F2(x,y,z) for(int x=y;x<=z;x++)
#define F3(x,y,z) for(int x=y;x>z;x--)
#define F4(x,y,z) for(int x=y;x>=z;x--)
#define pb push_back
#define LL long long
#define co complex<double>
 
#define MAX 100005
#define AMAX 1500
#define MOD 1000000007

#define f(c,d) ((1<<(c))*(d))

using namespace std;

int n,m;
double x[1005][1005],y[2][1005],ta;

int main(){
    while(scanf("%d%d",&n,&m)==2){
        F1(a,0,m)y[0][a]=y[1][a]=0;
        F1(a,0,n){
            ta=0;
            F1(b,0,m){
                scanf("%lf",&x[a][b]);
                ta+=x[a][b];
            }
            F1(b,0,m){
                x[a][b]/=ta;
                y[0][b]+=x[a][b];
                y[1][b]+=x[a][b]*x[a][b];
            }
        }
        ta=0;
        F1(a,0,m)ta+=y[0][a]+y[0][a]*y[0][a]-y[1][a];
        printf("%.2lf\n",ta);
    }
    //system("pause");
    return 0;
}