#include <bits/stdc++.h>
using namespace std;
int n, l, k, a[205];
double ans, p[205];
double dp[205][205][405];
int main() {
  scanf("%d %d %d", &n, &l, &k);
  for (int i = 1; i <= n; ++i) scanf("%lf", &p[i]), p[i] /= 100.0;
  for (int i = 1; i <= n; ++i) scanf("%d", a + i);
  dp[0][0][200 + k] = 1;
  for (int i = 1; i <= n; ++i)
    for (int j = 0; j < i; ++j)
      for (int k = 0; k <= 400; ++k) {
        if (~a[i])
          dp[i][j + 1][min(k + a[i], 400)] += dp[i - 1][j][k] * p[i];
        else if (k > 0)
          dp[i][j + 1][k - 1] += dp[i - 1][j][k] * p[i];
        dp[i][j][k] += dp[i - 1][j][k] * (1 - p[i]);
      }
  for (int i = l; i <= n; ++i)
    for (int j = 200; j <= 400; ++j) ans += dp[n][i][j];
  printf("%.12f\n", ans);
  return 0;
}
