#include <bits/stdc++.h>
using namespace std;
const int N = 205;
int n, l, k, i, j, a[N];
double f[N][N][2 * N + 10], p[N], ans;
int main() {
  cin >> n >> l >> k;
  f[0][0][k + 200] = 1;
  for (i = 1; i <= n; i++) cin >> p[i], p[i] = p[i] / 100.0;
  for (i = 1; i <= n; i++) cin >> a[i];
  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++)
      for (int o = 0; o <= 400; o++) {
        int tmp = o + a[i + 1];
        if (tmp > 400) tmp = 400;
        f[i + 1][j + 1][tmp] += f[i][j][o] * p[i + 1];
        f[i + 1][j][o] += f[i][j][o] * (1 - p[i + 1]);
      }
  for (i = l; i <= n; i++)
    for (j = 200; j <= 400; j++) ans += f[n][i][j];
  printf("%.9f\n", ans);
}
