#include <bits/stdc++.h>
using namespace std;
const int maxn = 250;
int A[maxn], op[maxn];
double p[maxn];
double dp[maxn][maxn][450];
int main() {
  int n, l, K;
  scanf("%d%d%d", &n, &l, &K);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &A[i]);
    p[i] = 1.0 * A[i] / 100;
  }
  for (int i = 1; i <= n; i++) scanf("%d", &op[i]);
  dp[0][0][K + 200] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= i; j++) {
      for (int k = 0; k <= 400; k++) {
        dp[i + 1][j][k] += dp[i][j][k] * (1 - p[i + 1]);
        if (op[i + 1] == -1) {
          if (k) dp[i + 1][j + 1][k - 1] += dp[i][j][k] * p[i + 1];
        } else {
          dp[i + 1][j + 1][min(400, k + op[i + 1])] += dp[i][j][k] * p[i + 1];
        }
      }
    }
  }
  double ans = 0;
  for (int i = l; i <= n; i++) {
    for (int k = 200; k <= 400; k++) ans += dp[n][i][k];
  }
  printf("%.12f\n", ans);
  return 0;
}
