import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone {
	public static void main (String[] args) {
		Scanner x = new Scanner(System.in);
		double p = 1, a ;
		int c = 0;
		while( x.hasNext() ) {
			a = x.nextDouble();
			if(a >= 0) {
				c++;
				p*=a;
			} else break;
		}
		System.out.printf("%.2f", Math.pow(p,1.0/c) );
	}
}