#pragma warning (disable : 4996)

#include <stdlib.h>
#include <iostream>
#include <vector>
#include <string>
#include <assert.h>
#include <stack>
#include <algorithm>
#include <ios>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <queue>
#include <set>
#include <functional>
#include <cmath>
#include <sstream>
#include <map>
#include <memory.h>
#include <stdio.h>
#include <cassert>
#include <string.h>

#define forn(i , n) for (int i = 0; i < n; ++i)
#define down(i, n) for (int i = n - 1; i >= 0; --i)


using namespace std;

typedef unsigned long long int u64;
typedef long long int i64;
typedef vector<i64> vint;
typedef vector<i64> vi64;
typedef pair<int, int> pint;
typedef pair<i64, i64> pi64;

#define FILE_NAME "file"
#define M_PI 3.14159265358979323846

double sqr(double a)
{
    return a * a;
}

struct Node
{
    vector<int> nbr;
    int used;
    int p1, p2;
    int init, goal;
    Node()
    {
        p1 = p2 = 0;
        used = 0;
    }
};

#define MAXN 300000
#define MODULE 1000000009


struct St
{
    int n, m;
    bool operator<(const St & b) const{
        if (n !=b.n)
        {
            return n < b.n;
        }
        else
            return m < b.m;
    }

};

double leng(pint a, pint b)
{
    double c = sqr(a.first - b.first) + sqr(a.second - b.second);
    return sqrt(c);
}

double getL(vector<pint> & a)
{
    double ans = 0;
    forn(i, 3)
    {
        ans += leng(a[i], a[i + 1]);
    }
    return ans;
}


int main()
{
    clock_t start = clock();
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout << fixed << setprecision(15);
#ifdef FILE_INPUT
    freopen(FILE_NAME ".in", "r", stdin);
    freopen(FILE_NAME ".out", "w", stdout);
#endif
    vector<pint> arr;
    int n, m;
    cin >> n >> m;
    double ans = 0;
    double s = n * m - 1;

    ans = ((m - 1)*(n - 1) / s + 1) / n;
    //ans *= m;
    cout << ans;
    return 0;
}