#include <bits/stdc++.h>
using namespace std;
int n, m;
int main() {
  cin >> n >> m;
  if (n == 1) {
    cout << 1;
    exit(0);
  }
  cout << fixed << setprecision(12)
       << 1.0 / n + (1.0 * (n - 1)) / n * (1.0 * (m - 1)) / (m * n - 1);
}
