#include <stdlib.h>
#include <stdio.h>
#include <strings.h>

int main() {
	const float coeff[] = {.1, .1, .09, .09, .08, .06, .05, .04, .02, .01, 0, -.01, -.02, -.02, -.02, -.02, -.02, -.02, -.01, -.01, 0, 0, .01, .01, .01, .01, .01, .01, .01, 1};	//Jednicka je zarazka!
	
	size_t coefs = 0;
	while (coeff[++coefs] < 1);	//Pocet koeficientu
	
	float history[coefs];
	bzero(&history, coefs * sizeof(float));	//Vynulovani
	
	float x;
	while (scanf("%f", &x) != EOF) {
		//printf("%f\n", x);
		
		//Posun prvku v poli
		for (size_t i = coefs; i > 0; i--) {
			history[i] = history[i - 1];
		}
		history[0] = x;
		//printa(history, coefs);
		
		//FIR
		float out = 0;
		for (size_t i = 0; i < coefs; i++) {
			out += history[i] * coeff[i];
		}
		
		printf("%f\n", out);
	}
	return EXIT_SUCCESS;
}