public class Exercise5 {
	/*
	 * 1h enallaktiki
	 */
	
	public static void main(String[] argv) {
		
		Double x = Double.valueOf(argv[0]);

		double term = 1.0;
		double sum = 0.0;
		for (int n=1; sum!=sum + term; n++){
			sum += term;
			term = 1.0;
				for (int i=1; i<=n; i++) 
					term *= x/i;
		}
		System.out.println(term);
	}
	
	
	
	/*
	 * 2h enallaktiki
	 */
	/*
	public static void main(String[] argv) {
		
		Double x = Double.valueOf(argv[0]);

		double term = 1.0;
		double sum = 0.0;
		for (int n=1; sum!=sum + term; n++){
			sum += term;
			term *= x/n;
		}
		System.out.println(term);
	}
	*/
}