#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 10;
const int UB = 1000;
int w, b;
double dp[N][N];
int main() {
  for (int j = 0; j <= UB; ++j) dp[0][j] = 0;
  for (int i = 1; i <= UB; ++i) dp[i][0] = 1;
  for (int i = 1; i <= UB; ++i) {
    for (int j = 1; j <= UB; ++j) {
      double sum = 0;
      if (j >= 3)
        sum += ((j - 1) * (j - 2) * dp[i][j - 3]) / ((i + j - 1) * (i + j - 2));
      if (i >= 1 && j >= 2)
        sum += ((j - 1) * i * dp[i - 1][j - 2]) / ((i + j - 1) * (i + j - 2));
      dp[i][j] = (i + j * sum) / (i + j);
    }
  }
  while (scanf("%d%d", &w, &b) == 2) printf("%.10f\n", dp[w][b]);
  return 0;
}
