#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-9;
const double pi = acos(-1.0);
const long long oo = 1LL << 60;
const int N = 310;
double res;
double p[N], dp[N][N][N];
int n, a[N];
int main(void) {
  int l, k, i, j;
  scanf("%d%d%d", &n, &l, &k);
  for (int i = 1; i <= n; i++) scanf("%lf", p + i), p[i] /= 100.0;
  for (int i = 1; i <= n; i++) scanf("%d", a + i), a[i]++;
  if (k < n)
    dp[0][0][k] = 1;
  else
    dp[0][0][n] = 1;
  for (i = 0; i < n; i++)
    for (j = 0; j <= i; j++)
      for (k = 0; k <= n; k++) {
        dp[i + 1][j + 1][min(n, k + a[i + 1])] += dp[i][j][k] * p[i + 1];
        dp[i + 1][j][k] += (1 - p[i + 1]) * dp[i][j][k];
      }
  for (int i = l; i <= n; i++)
    for (int j = i; j <= n; j++) res += dp[n][i][j];
  printf("%.10lf\n", res);
  return 0;
}
