#include <bits/stdc++.h>
using namespace std;
double an[202][202][405], p[201];
int b[201];
int main() {
  int n, l, k;
  scanf("%d%d%d", &n, &l, &k);
  for (int i = 1; i < n + 1; ++i) {
    int t;
    scanf("%d", &t);
    p[i] = t / 100.0;
  }
  an[0][0][k + 201] = 1.0;
  for (int i = 1; i < n + 1; ++i) scanf("%d", b + i);
  for (int i = 1; i < n + 1; ++i) {
    for (int j = 0; j < n + 1; ++j)
      for (int k = 0; k < 405; ++k)
        an[i][j][k] = an[i - 1][j][k] * (1.0 - p[i]);
    if (b[i] == -1)
      for (int j = 1; j < n + 1; ++j)
        for (int k = 0; k < 404; ++k)
          an[i][j][k] += an[i - 1][j - 1][k + 1] * p[i];
    else
      for (int j = 1; j < n + 1; ++j) {
        for (int k = b[i]; k < 403; ++k)
          an[i][j][k] += an[i - 1][j - 1][k - b[i]] * p[i];
        for (int k = 403 - b[i]; k < 404; ++k)
          an[i][j][403] += an[i - 1][j - 1][k] * p[i];
      }
  }
  double r = 0;
  for (int i = l; i < n + 1; ++i)
    for (int j = 201; j < 404; ++j) r += an[n][i][j];
  printf("%0.7lf", r);
}
