#include <bits/stdc++.h>
using namespace std;
double dp[201][501][201], prob[200];
int prize[200];
int main() {
  int n, x, l, k, i, j, a;
  cin >> n >> l >> k;
  for (int i = 0; i < n; ++i) {
    cin >> a;
    prob[i] = (double)a / 100;
  }
  for (int i = 0; i < n; ++i) cin >> prize[i];
  dp[0][200 + k][0] = 1;
  for (i = 0; i < n; ++i) {
    for (x = 0; x <= i; ++x) {
      for (j = 0; j <= 500; ++j) {
        int net = min(500, j + prize[i]);
        if (j + prize[i] >= 0) dp[i + 1][net][x + 1] += dp[i][j][x] * prob[i];
        dp[i + 1][j][x] += dp[i][j][x] * (1 - prob[i]);
      }
    }
  }
  double ret = 0;
  for (i = 200; i <= 500; ++i)
    for (j = l; j <= n; ++j) ret += dp[n][i][j];
  printf("%0.9lf\n", ret);
}
