#include <bits/stdc++.h>
using namespace std;
const int maxn = 201;
int p[maxn], a[maxn], N, L, K;
long double f[maxn][maxn][maxn * 2];
int main() {
  scanf("%d%d%d", &N, &L, &K);
  for (int i = 0; i < N; ++i) scanf("%d", &p[i]);
  for (int i = 0; i < N; ++i) scanf("%d", &a[i]);
  f[0][0][N + min(N, K)] = 1;
  for (int i = 0; i < N; ++i)
    for (int j = 0; j <= N; ++j)
      for (int k = -N; k <= N; ++k)
        if (f[i][j][N + k] > 0) {
          f[i + 1][j + 1][N + min(k + a[i], N)] +=
              p[i] * 1.0 / 100 * f[i][j][N + k];
          f[i + 1][j][N + k] += (100 - p[i]) * 1.0 / 100 * f[i][j][N + k];
        }
  long double ans = 0;
  for (int j = L; j <= N; ++j)
    for (int k = N; k <= N + N; ++k) ans += f[N][j][k];
  cout << ans << endl;
}
