#include <bits/stdc++.h>
using namespace std;
const int N = 200;
double dp[N + 1][N + 1][N + N + 2];
int a[N + 2];
double p[N + 2];
int n, m, c;
int main() {
  scanf("%d%d%d", &n, &m, &c);
  c = min(n, c);
  for (int i = 1; i <= n; i++) {
    scanf("%lf", &p[i]);
    p[i] = p[i] * 0.01;
  }
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
  }
  dp[0][0][c + n] = 1.0;
  for (int i = 1; i <= n; i++) {
    dp[i][0][c + n] = dp[i - 1][0][c + n] * (1 - p[i]);
    for (int j = 1; j <= i; j++) {
      for (int k = max(0, a[i]); k <= n + n; k++) {
        dp[i][j][k] += p[i] * dp[i - 1][j - 1][k - a[i]];
      }
      for (int k = 0; k <= n + n; k++) {
        dp[i][j][k] += (1 - p[i]) * dp[i - 1][j][k];
      }
      for (int k = max(n + n - a[i] + 1, 0); k <= n + n; k++) {
        dp[i][j][n + n] += p[i] * dp[i - 1][j - 1][k];
      }
    }
  }
  double ans = 0.0;
  for (int i = m; i <= n; i++) {
    for (int j = n; j <= n + n; j++) ans += dp[n][i][j];
  }
  printf("%.12lf\n", ans);
  return 0;
}
