#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
int n, mn, t, a[210];
double p[210], dp[210][610][210], ans = 0;
int main() {
  cin >> n >> mn >> t;
  for (int i = 0; i < n; i++) cin >> p[i];
  for (int i = 0; i < n; i++) cin >> a[i];
  dp[0][205 + t][0] = 1;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < 608; j++) {
      for (int k = 0; k < i + 1; k++) {
        if (dp[i][j][k] == 0) continue;
        if (a[i] == -1) {
          dp[i + 1][j - 1][k + 1] += dp[i][j][k] * p[i] / 100.0;
          dp[i + 1][j][k] += dp[i][j][k] * (100.0 - p[i]) / 100.0;
        } else {
          dp[i + 1][min(600, j + a[i])][k + 1] += dp[i][j][k] * p[i] / 100.0;
          dp[i + 1][j][k] += dp[i][j][k] * (100.0 - p[i]) / 100.0;
        }
      }
    }
  }
  for (int i = 205; i < 608; i++)
    for (int j = mn; j <= n; j++) ans += dp[n][i][j];
  printf("%.10lf\n", ans);
  return 0;
}
