#include <bits/stdc++.h>
using namespace std;
int N, M;
int main() {
  scanf("%d", &(N)), scanf("%d", &(M));
  double dp[N + 1];
  for (int i = (0); i < (N + 1); i++) dp[i] = 0;
  dp[0] = 1;
  double ndp[N + 1];
  for (int COUNTER = (0); COUNTER < (N); COUNTER++) {
    for (int i = (0); i < (N + 1); i++) ndp[i] = 0;
    for (int i = (0); i < (N); i++) {
      double c = (double)(M - i) / (N * M - COUNTER);
      ndp[i + 1] += dp[i] * c;
      ndp[i] += dp[i] * (1 - c);
    }
    for (int i = (0); i < (N + 1); i++) dp[i] = ndp[i];
  }
  double sum = 0;
  for (int i = (0); i < (N + 1); i++) {
    dp[i] *= i;
    sum += dp[i];
  }
  for (int i = (0); i < (N + 2); i++) dp[i] /= sum;
  double ans = 0;
  for (int i = (0); i < (N + 1); i++) {
    ans += dp[i] * ((double)i / N);
  }
  printf("%.12lf\n", ans);
}
