// 台形則による数値積分

import java.util.Random;
import java.io.*;

public class Int_expb{
    public static void main(String[] args) throws IOException {
	double x0=0.0, x, y, h, s=0.0, sreal, serror;
	String str;

        BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Input: Number of trials");
        str = buf.readLine();
        long ntrial = Long.parseLong(str);
	h=1.0/ntrial;

	x = x0;
	y = Math.exp(-x);
	s = s + 0.5*y;

	for(int j=1; j <= ntrial-1; j++){
	    x = x + h;
	    y = Math.exp(-x);
	    s = s + y;
	}

	x = x + h;
	y = Math.exp(-x);
	s = s + 0.5*y;
	s = s / ntrial;
	sreal = 1.0 - Math.exp(-1.0);
	serror = s - sreal;

	System.out.println(" ntrial="+ntrial);	    
	System.out.println(" s= "+s);	    
	System.out.println(" sreal= "+sreal);	    
	System.out.println(" serror= "+serror);	    

	
    }

}