#include <bits/stdc++.h>
using namespace std;
double ans, p[10001], f[305][305][305];
int n, l, k, a[10001];
int i, j;
int main() {
  scanf("%d %d %d", &n, &l, &k);
  for (i = 1; i <= n; i++) scanf("%lf", &p[i]), p[i] /= 100.0;
  for (i = 1; i <= n; i++) scanf("%d", &a[i]), a[i]++;
  if (k < n)
    f[0][0][k] = 1;
  else
    f[0][0][n] = 1;
  for (i = 0; i < n; i++)
    for (j = 0; j <= i; j++)
      for (k = 0; k <= n; k++) {
        if (n < k + a[i + 1])
          f[i + 1][j + 1][n] += (p[i + 1]) * f[i][j][k];
        else
          f[i + 1][j + 1][k + a[i + 1]] += (p[i + 1]) * f[i][j][k];
        f[i + 1][j][k] += ((1 - p[i + 1]) * f[i][j][k]);
      }
  for (i = l; i <= n; i++)
    for (j = i; j <= n; j++) ans += f[n][i][j];
  printf("%.10lf\n", ans);
}
