#include <bits/stdc++.h>
using namespace std;
double ans, p[205], f[205][205][205];
int a[205], n, l, K;
int main() {
  scanf("%d%d%d", &n, &l, &K);
  K = min(K, n);
  f[0][K][0] = 1;
  for (int i = 1; i <= n; i++) scanf("%lf", &p[i]), p[i] /= 100;
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
  for (int i = 1; i <= n; i++)
    for (int j = 0; j <= n; j++)
      for (int k = 0; k <= n; k++)
        if (f[i - 1][j][k]) {
          f[i][j][k] += f[i - 1][j][k] * (1 - p[i]);
          if (a[i] == -1)
            f[i][j][k + 1] += f[i - 1][j][k] * p[i];
          else
            f[i][min(j + a[i] + 1, n)][k + 1] += f[i - 1][j][k] * p[i];
        }
  for (int j = l; j <= n; j++)
    for (int k = l; k <= j; k++) ans += f[n][j][k];
  printf("%.8lf\n", ans);
}
