#include<iostream>
#include<algorithm>
#include<string>
#include<cstdlib>
#include<map>
#include<iomanip>
#include<sstream>
#include<vector>
#include<stack>
#include<math.h>
#include<queue>
#include<complex>
using namespace std;

int main() {
  
	cout << fixed << setprecision(10);
  	long double a,b;
  cin>>a>>b;
  cout<<1.0/(1.0/a+1.0/b)<<endl;
} 
