#include  <bits/stdc++.h> 
#include<string>
#include <algorithm>
using namespace std;

void solve(){
	float n,k;
	float sum;
	cin>>n>>k;
	for (int i = 0; i <= n; ++i)
	{
		for (int j = 0; j < k; ++j)
		{
			sum += (1/((n+1)*k))*i;
		}
	}
	cout<<sum;
}

int main() {
	solve();
}