#include<stdio.h>

int main(void){
    float n,s;
    int i;
    while (scanf("%f",&n) != EOF){
    scanf("%f",&n);
        s = n;
        for (i = 2;i <= 10;i++){
            if (i % 2 == 0){
                n = n * 2.00f;
                s = s + n;
            }
            else{
                n = n / 3.00f;
                s = s + n;
            }
        }
        printf("%f\n",s);
    }
    return 0;
}