#include <bits/stdc++.h>
double f[1010][1010];
int main() {
  int i, j, n, m;
  double w, b;
  scanf("%d%d", &n, &m);
  for (i = 1; i <= n; i++)
    for (j = 0; j <= m; j++) {
      w = i, b = j;
      f[i][j] = w / (w + b);
      if (j > 1)
        f[i][j] += b / (w + b) * (b - 1) / (w + b - 1) * w / (w + b - 2) *
                   f[i - 1][j - 2];
      if (j > 2)
        f[i][j] += b / (w + b) * (b - 1) / (w + b - 1) * (b - 2) / (w + b - 2) *
                   f[i][j - 3];
    }
  printf("%.12lf\n", f[n][m]);
  return 0;
}
