#include <bits/stdc++.h>
using namespace std;
double dp[202][202][202 << 1];
double p[202];
int w[202];
int main() {
  int n, l, s;
  scanf("%d%d%d", &n, &l, &s);
  for (int i = 1, x; i <= n; ++i) {
    scanf("%d", &x);
    p[i] = 1.0 * x / 100;
  }
  for (int i = 1; i <= n; ++i) scanf("%d", w + i);
  memset(dp, 0, sizeof(dp));
  dp[0][0][s + 200] = 1;
  for (int i = 1; i <= n; ++i)
    for (int j = 0; j < i; ++j)
      for (int k = 1; k <= 400; ++k) {
        dp[i][j][k] += dp[i - 1][j][k] * (1.0 - p[i]);
        dp[i][j + 1][min(400, k + w[i])] += dp[i - 1][j][k] * p[i];
      }
  double ans = 0;
  for (int i = l; i <= n; ++i)
    for (int j = 200; j <= 400; ++j) ans += dp[n][i][j];
  printf("%.12f\n", ans);
}
