Problem:
Score : 100 points

Problem Statement

Given is an integer N.

Takahashi chooses an integer a from the positive integers not greater than N with equal probability.

Find the probability that a is odd.

Constraints

1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:

N

Output

Print the probability that a is odd.
Your output will be considered correct when its absolute or relative error from the judge's output is at most 10^{-6}.

Sample Input 1

4

Sample Output 1

0.5000000000

There are four positive integers not greater than 4: 1, 2, 3, and 4. Among them, we have two odd numbers: 1 and 3. Thus, the answer is \frac{2}{4} = 0.5.

Sample Input 2

5

Sample Output 2

0.6000000000

Sample Input 3

1

Sample Output 3

1.0000000000

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigDecimal;
import java.util.Map.Entry;
import java.util.TreeMap;

public class Main {

	/* several useful subroutines */
	private static BufferedReader brStdin = new BufferedReader(new InputStreamReader(System.in));
	private static String[] readBuf = null;
	private static int readPtr = 0;
	private static String getString() throws IOException {
		while ( readBuf == null || readPtr >= readBuf.length ) {
			readBuf = brStdin.readLine().split(" ");
			readPtr = 0;
		}
		return readBuf[readPtr++];
	}
	private static int getInt() throws IOException {
		return Integer.parseInt(getString());
	}
	private static long getLong() throws IOException {
		return Long.parseLong(getString());
	}
	private static BigDecimal getBD() throws IOException {
		return new BigDecimal(getString());
	}
	@SuppressWarnings("unused")
	private static String[] getStringArray(int size) throws IOException {
		String stringArray[] = new String[size];
		for (int i = 0; i < stringArray.length; i++) {
			stringArray[i] = getString();
		}
		return stringArray;
	}
	@SuppressWarnings("unused")
	private static int[] getIntArray(int size) throws IOException {
		int intArray[] = new int[size];
		for (int i = 0; i < intArray.length; i++) {
			intArray[i] = getInt();
		}
		return intArray;
	}
	@SuppressWarnings("unused")
	private static long[] getLongArray(int size) throws IOException {
		long longArray[] = new long[size];
		for (int i = 0; i < longArray.length; i++) {
			longArray[i] = getLong();
		}
		return longArray;
	}
	@SuppressWarnings("unused")
	private static BigDecimal[] getBDArray(int size) throws IOException {
		BigDecimal bdArray[] = new BigDecimal[size];
		for (int i = 0; i < bdArray.length; i++) {
			bdArray[i] = getBD();
		}
		return bdArray;
	}

	
	/* main routine */
	public static void main(String args[]) throws IOException {
		int n = getInt();
		double d = n;
		System.out.println( 1d - (n/2 / d) );
	}
}