#include <bits/stdc++.h>
using namespace std;
map<pair<int, pair<int, int> >, double> PD;
int n, l, k;
double prob[256];
int v[256];
double calc(int saco, int u, int towin) {
  if (saco > (n - u + 2)) saco = (n - u + 2);
  if (u == n) return (saco >= 0 and towin == 0 ? 1.0 : 0.0);
  map<pair<int, pair<int, int> >, double>::iterator PDi =
      PD.find(pair<int, pair<int, int> >(saco, pair<int, int>(u, towin)));
  if (PDi != PD.end()) return PDi->second;
  double soma = 0.0;
  soma += prob[u] * calc(saco + v[u], u + 1, (towin - 1 > 0 ? towin - 1 : 0));
  soma += (1.0 - prob[u]) * calc(saco, u + 1, towin);
  PD[pair<int, pair<int, int> >(saco, pair<int, int>(u, towin))] = soma;
  return soma;
}
int main() {
  scanf("%d %d %d", &n, &l, &k);
  for (int i = 0; i < n; i++) {
    int p;
    scanf("%d", &p);
    prob[i] = (double)p / 100.0;
  }
  for (int i = 0; i < n; i++) scanf("%d", v + i);
  PD.clear();
  printf("%.12lf\n", calc(k, 0, l));
  return 0;
}
