#include <bits/stdc++.h>
using namespace std;
int n, l, k, i, p[256], a[256], j, w;
double f[201][512][201], aa;
int main() {
  scanf("%d%d%d", &n, &l, &k);
  k = min(k, n);
  for (i = 0; i < n; ++i) scanf("%d", p + i);
  for (i = 0; i < n; ++i) scanf("%d", a + i);
  f[0][k + 256][0] = 1;
  for (i = 0; i < n; ++i)
    for (j = -i; j <= n; ++j)
      for (w = 0; w <= i; ++w)
        if (f[i][j + 256][w] > 0) {
          f[i + 1][256 + min(j + a[i], n)][w + 1] +=
              f[i][j + 256][w] * p[i] / 100;
          f[i + 1][j + 256][w] += f[i][j + 256][w] * (100 - p[i]) / 100;
        }
  for (j = 0; j <= n; ++j)
    for (w = l; w <= n; ++w) aa += f[n][j + 256][w];
  printf("%.12lf\n", aa);
  return 0;
}
