#include <bits/stdc++.h>
using namespace std;
int n, l, k, a[201];
double p[201], dp[201][201][401] = {{{0}}}, ans;
int main(void) {
  int i, j;
  cin >> n >> l >> k;
  for (i = 1; i <= n; ++i) {
    cin >> p[i];
    p[i] /= 100;
  }
  for (i = 1; i <= n; ++i) cin >> a[i];
  if (k > n)
    dp[0][0][2 * n] = 1;
  else
    dp[0][0][n + k] = 1;
  for (i = 0; i < n; ++i)
    for (j = 0; j <= l; ++j)
      for (k = 0; k <= 2 * n; ++k) {
        dp[i + 1][j][k] += dp[i][j][k] * (1 - p[i + 1]);
        int t = k + a[i + 1];
        if (t > 2 * n) t = 2 * n;
        if (t < 0) t = 0;
        int t2 = j + 1;
        if (t2 > l) t2 = l;
        dp[i + 1][t2][t] += dp[i][j][k] * p[i + 1];
      }
  ans = 0;
  for (i = n; i <= 2 * n; ++i) ans += dp[n][l][i];
  printf("%.10lf", ans);
  return 0;
}
