#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:16777216")
using namespace std;
const double eps = 1e-9;
const double pi = acos(-1.0);
double p[222];
int a[222];
double dp[222][222][444];
int main() {
  int n, l, k;
  cin >> n >> l >> k;
  for (int i = 0; i < n; i++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  dp[0][0][222] = 1.0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      for (int k = 0; k < 444; k++)
        if (dp[i][j][k] != 0.0) {
          dp[i + 1][j + 1][min(k + a[i], 443)] += dp[i][j][k] * p[i];
          dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i]);
        }
    }
  }
  double res = 0.0;
  for (int i = l; i <= n; i++) {
    for (int j = 222 - k; j < 444; j++) {
      res += dp[n][i][j];
    }
  }
  printf("%.12lf\n", res);
  return 0;
}
