#include <bits/stdc++.h>
using namespace std;
double p[210];
int a[210];
double dp[210][210][210];
int main(void) {
  int N, L, K, i, j, k;
  cin >> N >> L >> K;
  for ((i) = 0; (i) < (int)(N); (i)++) cin >> p[i];
  for ((i) = 0; (i) < (int)(N); (i)++) cin >> a[i];
  for ((i) = 0; (i) < (int)(N); (i)++) p[i] /= 100.0;
  dp[0][0][0] = 1.0;
  for ((i) = 0; (i) < (int)(N); (i)++)
    for ((j) = 0; (j) < (int)(i + 1); (j)++)
      for ((k) = 0; (k) < (int)(N + 1); (k)++) {
        int c = a[i] + 1;
        dp[i + 1][j + 1][min(k + c, N)] += dp[i][j][k] * p[i];
        dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i]);
      }
  double ans = 0.0;
  for ((i) = 0; (i) < (int)(N + 1); (i)++)
    for ((j) = 0; (j) < (int)(N + 1); (j)++)
      if (i >= L && K + j - i >= 0) ans += dp[N][i][j];
  printf("%.9f\n", ans);
  return 0;
}
