#include <iostream>
#include <vector>
#include <algorithm>

#define INPUT_FROM_FILE (0) 
#if INPUT_FROM_FILE
#include <fstream>
#endif

int main(){
	double a, pre_a;
	double result = 0;

#if INPUT_FROM_FILE
	//std::ifstream ifs("test.txt");
	FILE *fp = fopen("test.txt", "r");
#endif

#if INPUT_FROM_FILE
	while(fscanf(fp, "%lf", &a) != EOF){
#else
	while(scanf("%lf", &a) != EOF){
#endif

		result = a;

		pre_a = a;
		for(int i = 2; i <= 10; i++){
			if(i % 2 == 0){
				a = 2 * pre_a;
			}
			else{
				a = pre_a / 3.0;
			}
			result += a;
			pre_a = a;
		}
		printf("%.7lf\n", result);
	}

#if INPUT_FROM_FILE
	fclose(fp);
#endif
	return 0;
}
