#include <bits/stdc++.h>
using namespace std;
double dp[200 + 10][200 + 10][200 + 10], p[200 + 10], ans = 0.0;
int n, l, k, a[200 + 10];
int main() {
  scanf("%d %d %d", &n, &l, &k);
  for (int i = 0; i < n; i++) scanf("%lf", p + i), p[i] /= 100.0;
  for (int i = 0; i < n; i++) scanf("%d", a + i), a[i]++;
  dp[0][0][k] = 1.0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j <= i; j++)
      for (int m = 0; m <= 200; m++) {
        dp[i + 1][j + 1][min(200, m + a[i])] += p[i] * dp[i][j][m];
        dp[i + 1][j][m] += (1.0 - p[i]) * dp[i][j][m];
      }
  for (int i = l; i <= n; i++)
    for (int j = i; j <= 200; j++) ans += dp[n][i][j];
  printf("%.12f", ans);
  return 0;
}
