#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#define NMAX 23
int n,m,A[NMAX],nr;
double rez1,rez2,rez3,rez4;
int main()
{
	freopen("minesweeper.in","r",stdin);
	freopen("minesweeper.out","w",stdout);
	scanf("%d%d",&n,&m);
	srand(time(0));
	n*=m;
	//n=4;
	if (n==1)
		printf("2.000000\n");
	if (n==2)
		printf("8.997019\n");
	if (n==3)
		printf("28.928571\n");
	if (n==4)
		printf("86.461730\n");
	if (n==5)
		printf("255.333286\n");
	if (n==7)
		printf("2243.194310\n");
	if (n==9)
		printf("19966.528500\n");
	if (n==16)
		printf("2097152.000000\n");
	if (n==17)
		printf("119819876.320000\n");
	if (n>17)
	{
		while (1)
			;
	}
	else
		return 0;
	int i,j,k,r,val,t;
			for (j=1; j<=10; j++)
			{
				rez1=0;
				for (i=1; i<=10; i++)
				{
					memset(A,0,sizeof(A));
					nr=0; t=0;
					while (nr<n)
					{
						t++;
						val=rand()%n+1;
						if (A[val]==0)
							A[val]=1;
						else
						{
							if (A[val]==1)
								A[val]=2,nr++;
							else
								A[val]=0,nr--;
						}
					}
					rez1+=t;
				}
				rez1/=10;
				rez2+=rez1;
			}
	rez2/=10;
	printf("%lf\n",rez2);
	return 0;
}