#include <bits/stdc++.h>
using namespace std;
int n, L, K;
double dp[222][222][444];
double p[222];
int a[222];
int main() {
  cin >> n >> L >> K;
  for (int i = 0; i < n; ++i) {
    cin >> p[i];
    p[i] = p[i] / 100.0;
  }
  for (int i = 0; i < n; ++i) cin >> a[i];
  dp[0][0][min(K + n, 2 * n)] = 1.0;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j < n; ++j)
      for (int k = 0; k <= 2 * n; ++k) {
        if (a[i] == -1) {
          if (k > 0) dp[i + 1][j + 1][k - 1] += dp[i][j][k] * p[i];
        } else {
          int kk = min(k + a[i], 2 * n);
          dp[i + 1][j + 1][kk] += dp[i][j][k] * p[i];
        }
        dp[i + 1][j][k] += dp[i][j][k] * (1 - p[i]);
      }
  double res = 0.0;
  for (int l = L; l <= n; ++l)
    for (int k = n; k <= 2 * n; ++k) {
      res += dp[n][l][k];
    }
  printf("%.10lf\n", res);
  return 0;
}
