#include <bits/stdc++.h>
const int N = 1001;
double dp[N][N];
int main() {
  int i, j, a, b;
  scanf("%d%d", &a, &b);
  for (i = 1; i <= a; i++) dp[i][0] = 1.0;
  for (i = 1; i <= a; i++) {
    for (j = 1; j <= b; j++) {
      dp[i][j] = (double)i / (i + j);
      if (j >= 3)
        dp[i][j] += dp[i][j - 3] * j * (j - 1) * (j - 2) / (i + j) /
                    (i + j - 1) / (i + j - 2);
      if (j >= 2)
        dp[i][j] += dp[i - 1][j - 2] * j * (j - 1) * i / (i + j) / (i + j - 1) /
                    (i + j - 2);
    }
  }
  printf("%.9lf\n", dp[a][b]);
  return 0;
}
