#include<stdio.h>
#include<stdlib.h>

#define MIN(a,b) ((a)<(b)?(a):(b))
#define MAX(a,b) ((a)>(b)?(a):(b))
#define POS(i,j) ((i)*n+(j))

void initMAX(int *array,int n){
  const int t=~(1<<31);
  int i;
  for(i=0;i<n;i++){
    array[i]=t;
  }
  return;
}

void run(void){
  const int f=4;
  int n,p;
  scanf("%d%d",&n,&p);
  int *a=(int *)malloc(sizeof(int)*4*n);
  int i;
  for(i=0;i<n;i++){
    scanf("%d%d%d",a+POS(0,i),a+POS(1,i),a+POS(2,i));
    a[POS(3,i)]=1;
  }

  int *now=(int *)calloc(3*n+1,sizeof(int));
  int *next=(int *)calloc(3*n+1,sizeof(int));
  for(i=0;i<f;i++){
    now[i]=a[POS(i,0)];
  }

  for(i=1;i<n;i++){
    initMAX(next,p+1);
    int j;
    for(j=MAX(0,p-3*(n-i));j<=MIN(p,3*i);j++){
      int k;
      for(k=0;k<f;k++){
        next[j+k]=MIN(next[j+k],now[j]+a[POS(k,i)]);
      }
    }
    int *swap=next;
    next=now;
    now=swap;
  }

  printf("%.5lf\n",(double)now[p]/n);

  return;
}

int main(void){
  run();
  return 0;
}