#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <algorithm>
#include <iostream>
#define maxx 55
#define INF 0xffffff
using namespace std;int mm[maxx][maxx*maxx] , hour[maxx][maxx] ;
int lx[maxx] , ly[maxx*maxx] ;
int vistx[maxx] , visty[maxx*maxx] ;
int linkx[maxx*maxx] , linky[maxx*maxx] ;
int N , M ;void init()
{int i , j , k ;memset( hour , 0 , sizeof ( hour ));memset( mm , 0 , sizeof ( mm ));for ( i = 0 ; i < N ; i++ )for ( j = 0 ; j < M ; j++ )scanf ( "%d", &hour[i][j] );for ( i = 0 ; i < N ; i++ )//处理输入，将M台机器每台分为N份for ( j = 0 ; j < M ; j++ )for ( k = 0 ; k < N ; k++ )mm[i][j*N+k] = hour[i][j] * ( k+1 );M = N * M ;//二分图中Y集中共有N*M个点
    memset( lx , 127 , sizeof ( lx ));//将X集中点的顶标置为最大memset( ly , 0 , sizeof ( ly ));for ( i = 0 ; i < N ; i++ )for ( j = 0 ; j < M ; j++ )if ( mm[i][j] < lx[i] )lx[i] = mm[i][j] ;//初始化X集中点的顶标
}int find ( int x )
{int i ;vistx[x] = 1;for ( i = 0 ; i < M ; i++ )if ( !visty[i] && lx[x] + ly[i] == mm[x][i] ){visty[i] = 1 ;if ( linkx[i] == -1 || find ( linkx[i] )){linkx[i] = x;linky[x] = i ;return 1;}}return 0;
}void KM()
{int i  , j , k ;memset( linkx , -1 , sizeof ( linkx ));memset( linky , -1 , sizeof ( linky ));for ( i = 0 ; i < N ; i++ ){while ( 1 ){memset( vistx , 0 , sizeof ( vistx ));memset( visty , 0 , sizeof ( visty ));if ( find ( i ))//判断是否为完美匹配break;int minn = INF ;for ( j = 0  ; j < N ; j++ )if ( vistx[j] ){for ( k = 0 ; k < M ; k++ )if ( !visty[k] && mm[j][k] - lx[j] - ly[k] < minn )minn = mm[j][k] - lx[j] - ly[k] ;}for ( j = 0 ; j < N ; j++ )//调整顶标if ( vistx[j] )lx[j] += minn ;for ( j = 0 ; j < M ; j++ )if ( visty[j] )ly[j] -=minn ;}}int sum = 0;for ( i = 0 ; i < N ; i++ )sum += mm[i][linky[i]];//cout<<sum<<endl;printf ( "%.6lf\n" , 1.0 * sum / N );
}int main()
{int cas ;scanf ( "%d" , &cas );while ( cas-- ){scanf ( "%d%d" , &N , &M );init();KM();}return 0;
}