#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#include<inttypes.h>
#include<string.h>

typedef int32_t i32;

#define POS(dir,j) ((dir) * (n + 2) + (j))

void run (void) {
  i32 n;
  scanf ("%" SCNi32, &n);
  double p, q;
  scanf ("%lf%lf", &p, &q);
  double *now = (double *) calloc (2 * (n + 2), sizeof (double));
  double *next = (double *) calloc (2 * (n + 2), sizeof (double));
  now[POS(0, 1)] = 1;
  double ans = 0;
  for (i32 iter = 0; iter < 25000; iter++) {
    memset (next, 0, sizeof (double) * 2 * (n + 2));
    for (i32 dir = 0; dir < 2; dir++) {
      i32 dx = dir == 0 ? 1 : -1;
      for (i32 i = 1; i <= n; ++i) {
        next[POS(dir, i + dx)] += q * now[POS(dir, i)];
        next[POS(dir ^ 1, i - dx)] += p * now[POS(dir, i)];
      }
    }
    memcpy (now, next, sizeof (double) * 2 * (n + 2));
    ans += next[POS(0, 0)] + next[POS(1, 0)];
  }
  printf ("%.6f\n", ans);
}

int main (void) {
  run ();
  return 0;
}