#include<iostream>
#include<iomanip>
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<vector>
#include<cctype>
#define D (double)
using namespace std;
int n,m;
signed main()
{
	scanf("%d%d",&n,&m);
	printf("%.10lf",((D(1*1.0/((D(1*1.0/n))+(D(1*1.0/m)))))));
	return putchar(10),0;
}