#include <bits/stdc++.h>
using namespace std;
int w, b;
double dp[1005][1005];
double solve(int w, int b) {
  for (int i = 0; i <= w; i++) dp[i][0] = 1;
  for (int i = 0; i <= b; i++) dp[0][i] = 0;
  dp[0][0] = 0;
  for (int ii = 1; ii <= w; ii++) {
    for (int jj = 1; jj <= b; jj++) {
      double i = ii, j = jj;
      dp[ii][jj] = i / (i + j);
      if (j >= 3)
        dp[ii][jj] += dp[ii][jj - 3] * (j / (i + j)) * ((j - 1) / (i + j - 1)) *
                      ((j - 2) / (i + j - 2));
      if (j >= 2 && i >= 1)
        dp[ii][jj] += dp[ii - 1][jj - 2] * (j / (i + j)) *
                      ((j - 1) / (i + j - 1)) * (i / (i + j - 2));
    }
  }
  return dp[w][b];
}
int main() {
  cin >> w >> b;
  printf("%.10f\n", solve(w, b));
  return 0;
}
