#include <bits/stdc++.h>
using namespace std;
int n, l, K;
int p[205];
int a[205];
double dp[205][205][405], ans;
int main() {
  cin >> n >> l >> K;
  for (int i = 1; i <= n; i++) {
    cin >> p[i];
  }
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  dp[0][0][K + 200] = 1;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j <= i; j++) {
      for (int k = 0; k <= 400; k++) {
        if (j != 0) {
          dp[i][j][min(k + a[i], 400)] += dp[i - 1][j - 1][k] * p[i] / 100;
        }
        dp[i][j][k] += dp[i - 1][j][k] * (100 - p[i]) / 100;
      }
    }
  }
  ans = 0;
  for (int i = l; i <= n; i++) {
    for (int j = 200; j <= 400; j++) {
      ans += dp[n][i][j];
    }
  }
  printf("%.7lf\n", ans);
  return 0;
}
