#include<bits/stdc++.h>
#define range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) for(int i = 0; i < (b); i++)
#define all(a) (a).begin(), (a).end()
#define show(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
const int INF = 2000000000;
using namespace std;

int main(){
    double a, b;
    cin >> a >> b;

    cout <<fixed << setprecision(10) <<  1 / (1 / a + 1 / b) << endl;
}
