package chelper;

import io.InputReader;
import io.OutputWriter;
import misc.GCJSolution;
import misc.SimpleSavingChelperSolution;


public class TaskC extends GCJSolution {

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    wrapSolve(testNumber, in, out);
  }

  double eps = 1e-9;

  @Override
  public void solve(int testNumber) {
    int n = in.nextInt();
    int k = in.nextInt();

    double u = in.nextDouble();
    double[] a = in.nextDoubleArray(n);

    double min = 1.0;
    for (double v : a) {
      min = Math.min(v, min);
    }

    double l = 0.0;
    double r = 1.1;
    double goodAns = 0.0;

    while (r - l > eps) {
      double m = (r + l) / 2;
      double ma = Math.min(m, 1.0);

      double uLeft = u;
      double ans = 1;

      for (double v : a) {
        double uNeed = Math.max(0, ma - v);
        uLeft -= uNeed;
//        ans *= ma;
        ans *= Math.max(ma, v);
      }

      if (uLeft >= 0) {
        l = m;
        goodAns = Math.max(goodAns, ans);
      } else {
        r = m;
      }
    }

    out.println(goodAns);
  }
}