#include<stdio.h>
int main() {
    int usd_amount;
    double eur_amount;
    const double CONVERSION_RATE= 0.85;
    scanf("%d", &usd_amount );
    if (usd_amount < 0 ) {
        printf("Invalid input\n");
    }else{
    eur_amount = usd_amount * CONVERSION_RATE;
    printf("%.2f\n'," eur_amount);
    }
    return 0;
}