#include <bits/stdc++.h>
using namespace std;
double dp[210][410][210];
int main() {
  int n, l, k;
  cin >> n >> l >> k;
  int a[n];
  double p[n];
  for (int i = 0; i < int(n); i++) {
    int x;
    cin >> x;
    p[i] = x / 100.0;
  }
  for (int i = 0; i < int(n); i++) cin >> a[i];
  dp[0][k + 203][0] = 1;
  for (int i = 0; i < int(n); i++) {
    for (int c = 0; c < int(407); c++) {
      for (int l = 0; l < int(201); l++) {
        if (c + a[i] >= 0) {
          dp[i + 1][min(406, c + a[i])][l + 1] += dp[i][c][l] * p[i];
        }
        dp[i + 1][c][l] += dp[i][c][l] * (1 - p[i]);
      }
    }
  }
  double ans = 0;
  for (int c = 203; c <= 406; c++)
    for (int m = l; m <= 200; m++) {
      ans += dp[n][c][m];
    }
  printf("%.20f\n", ans);
}
