#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 200;
const int MAX_N2 = MAX_N * 2;
int ps[MAX_N], as[MAX_N];
double dp[MAX_N + 1][MAX_N + 1][MAX_N2 + 1];
int main() {
  int n, l, k;
  scanf("%d%d%d", &n, &l, &k);
  if (k > n) k = n;
  int n2 = n * 2;
  for (int i = 0; i < n; i++) scanf("%d", ps + i);
  for (int i = 0; i < n; i++) scanf("%d", as + i);
  dp[0][0][n + k] = 1.0;
  for (int i = 0; i < n; i++) {
    double p = (double)ps[i] / 100, q = 1.0 - p;
    int &ai = as[i];
    for (int j = 0; j <= n; j++)
      for (int h = 0; h <= n2; h++)
        if (dp[i][j][h] > 0.0) {
          int j1 = min(j + 1, n);
          int h1 = min(h + ai, n2);
          dp[i + 1][j1][h1] += dp[i][j][h] * p;
          dp[i + 1][j][h] += dp[i][j][h] * q;
        }
  }
  double sum = 0.0;
  for (int j = l; j <= n; j++)
    for (int h = n; h <= n2; h++) sum += dp[n][j][h];
  printf("%.12lf\n", sum);
  return 0;
}
