#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:65000000")
using namespace std;
int n, l, k;
double dyn[201][201][402];
double prob[200];
int what[200];
double eps = 1e-9;
int main() {
  scanf("%d%d%d", &n, &l, &k);
  for (int i = 0; i < n; ++i) {
    scanf("%lf", prob + i);
    prob[i] *= 0.01;
  }
  for (int j = 0; j < n; ++j) scanf("%d", what + j);
  dyn[0][0][200 + k] = 1;
  for (int i = 0; i < n; ++i)
    for (int j = 0; j <= i; ++j)
      for (int k = 0; k < 402; ++k) {
        dyn[i + 1][j + 1][min(k + what[i], 401)] += dyn[i][j][k] * prob[i];
        dyn[i + 1][j][k] += dyn[i][j][k] * (1.0 - prob[i]);
      }
  double sum = 0.0;
  for (int j = l; j <= n; ++j)
    for (int k = 200; k < 402; ++k) sum += dyn[n][j][k];
  printf("%.8lf\n", sum);
  return 0;
}
