#include <bits/stdc++.h>
using namespace std;
const int MAXN = 201;
double dp[MAXN][MAXN][MAXN], p[MAXN], ans;
int a[MAXN];
int main() {
  int i, j, k, N, L, K;
  scanf("%d %d %d", &N, &L, &K);
  for (i = 0; i < N; ++i) scanf("%lf", &p[i]), p[i] /= 100.0;
  for (i = 0; i < N; ++i) scanf("%d", &a[i]), ++a[i];
  dp[0][0][min(K, N)] = 1.0;
  for (i = 0; i < N; ++i)
    for (j = 0; j <= i; ++j)
      for (k = 0; k <= N; ++k) {
        dp[i + 1][j + 1][min(N, k + a[i])] += dp[i][j][k] * p[i];
        dp[i + 1][j][k] += dp[i][j][k] * (1.0 - p[i]);
      }
  for (j = L; j <= N; ++j)
    for (k = j; k <= N; ++k) ans += dp[N][j][k];
  printf("%.10lf", ans);
  return 0;
}
