#include <bits/stdc++.h>
using namespace std;
int ri() {
  int res;
  scanf("%d", &res);
  return res;
}
int numbits(int n) { return n ? 1 + numbits(n & (n - 1)) : 0; }
class timer {
 public:
  timer() : t_(clock()) {}
  void start() { t_ = clock(); }
  float elapsed() { return float(clock() - t_) / CLOCKS_PER_SEC; }

 private:
  clock_t t_;
};
double dp[1024][1024];
int main() {
  int n, m;
  cin >> n >> m;
  memset(dp, 0, sizeof(dp));
  dp[0][0] = 1.0;
  for (int i = 0; i <= m; ++i) {
    for (int j = 0; j < n; ++j) {
      if (dp[i][j] == 0.0) {
        continue;
      }
      int ones = m - i;
      int left = n * m - j;
      double p = 1.0 * ones / left;
      dp[i + 1][j + 1] += p * dp[i][j];
      dp[i][j + 1] += (1.0 - p) * dp[i][j];
    }
  }
  double res = 0.0;
  for (int i = 1; i <= min(n, m); ++i) {
    double p = 1.0 * i / n;
    double subres = dp[i][n] * p * p;
    res += subres;
  }
  printf("%.9f\n", res * n);
  return 0;
}
