#include <bits/stdc++.h>
using namespace std;
int n, m, k, a[300];
double p[300], d[202][202][402], ans;
int main() {
  scanf("%d%d%d", &n, &m, &k);
  for (int i = 1; i <= n; ++i) {
    scanf("%lf", &p[i]);
    p[i] /= 100;
  }
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &a[i]);
  }
  if (k >= n) k = n;
  d[0][0][k + n] = 1;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < n; ++j) {
      for (int l = 0; l <= 2 * n; ++l) {
        if (a[i + 1] != -1) {
          d[i + 1][j + 1][min(2 * n, l + a[i + 1])] += d[i][j][l] * p[i + 1];
          d[i + 1][j][l] += d[i][j][l] * (1 - p[i + 1]);
        }
        if (a[i + 1] == -1) {
          if (l > 0) d[i + 1][j + 1][l - 1] += d[i][j][l] * p[i + 1];
          d[i + 1][j][l] += d[i][j][l] * (1 - p[i + 1]);
        }
      }
    }
  }
  for (int i = n; i <= n; ++i) {
    for (int j = m; j <= n; ++j)
      for (int l = n; l <= 2 * n; ++l) {
        ans += d[i][j][l];
      }
  }
  printf("%.9lf", ans);
  return 0;
}
