#include <bits/stdc++.h>
using namespace std;
template <class T1>
void deb(T1 e) {
  cout << e << endl;
}
template <class T1, class T2>
void deb(T1 e1, T2 e2) {
  cout << e1 << " " << e2 << endl;
}
template <class T1, class T2, class T3>
void deb(T1 e1, T2 e2, T3 e3) {
  cout << e1 << " " << e2 << " " << e3 << endl;
}
template <class T1, class T2, class T3, class T4>
void deb(T1 e1, T2 e2, T3 e3, T4 e4) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << endl;
}
template <class T1, class T2, class T3, class T4, class T5>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << endl;
}
template <class T1, class T2, class T3, class T4, class T5, class T6>
void deb(T1 e1, T2 e2, T3 e3, T4 e4, T5 e5, T6 e6) {
  cout << e1 << " " << e2 << " " << e3 << " " << e4 << " " << e5 << " " << e6
       << endl;
}
template <class T>
T Abs(T x) {
  return x > 0 ? x : -x;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
long long Pow(long long B, long long P) {
  long long R = 1;
  while (P > 0) {
    if (P % 2 == 1) R = (R * B);
    P /= 2;
    B = (B * B);
  }
  return R;
}
int BigMod(long long B, long long P, long long M) {
  long long R = 1;
  while (P > 0) {
    if (P % 2 == 1) {
      R = (R * B) % M;
    }
    P /= 2;
    B = (B * B) % M;
  }
  return (int)R;
}
int n, l, k;
vector<int> prize;
vector<double> prb;
double dp[202][202][202];
double rec(int pos, int need_2_win, int bags) {
  if (pos >= n) {
    if (need_2_win >= l && bags + k >= need_2_win)
      return 1.00;
    else
      return 0.0;
  }
  double &ret = dp[pos][need_2_win][bags];
  if (ret > -.5) return ret;
  ret = 0.0;
  ret += (prb[pos] / 100.0) *
         rec(pos + 1, need_2_win + 1, min(200, bags + prize[pos]));
  ret += (max(100.0 - prb[pos], 0.0) / 100.0) * rec(pos + 1, need_2_win, bags);
  return ret;
}
int main(void) {
  double val;
  int a;
  scanf("%d %d %d", &n, &l, &k);
  for (int i = 0; i < n; i++) {
    scanf("%lf", &val);
    prb.push_back(val);
  }
  for (int i = 0; i < n; i++) {
    scanf("%d", &a);
    prize.push_back(a + 1);
  }
  memset(dp, -1, sizeof dp);
  double ans = rec(0, 0, 0);
  printf("%.12lf\n", ans);
  return 0;
}
