#include<bits/stdc++.h>
using namespace std;
int main(){
    long long a;
    cin >> a;
    a=a*4*10;
    cout << a/5;
}
				I2luY2x1ZGU8Yml0cy9zdGRjKysuaD4KdXNpbmcgbmFtZXNwYWNlIHN0ZDsKaW50IG1haW4oKXsKICAgIGxvbmcgbG9uZyBhOwogICAgY2luID4+IGE7CiAgICBhPWEqNCoxMDsKICAgIGNvdXQgPDwgYS81Owp9