#include<stdio.h>

FILE*f=fopen("minesweeper.in","r");
FILE*g=fopen("minesweeper.out","w");

int n,m;


#include<stdlib.h>
#include<ctime>
int t,i,ok,s,v[100],nr;
double x;

int main () {
	
	fscanf(f,"%d %d",&n,&m);
	
	n = n * m; srand(time(0)); int u;
	
	for ( t = 1 ; t <= 300000 ; ++t ){
		nr = n;
		while ( 1 ){
			u = rand() % n;
			if ( v[u] % 3 == 1 )	--nr;
			if ( v[u] % 3 == 2 )	++nr;
			++v[u];
			if ( !nr ){
				for ( i = 0 ; i < n ; ++i ){
					x += v[i]; v[i] = 0;
				}
				break ;
			}
		}
	}
	
	fprintf(g,"%.6lf\n",x/(t-1));
	
	fclose(f);
	fclose(g);
	
	return 0;
}