#include <iostream>
#include <math.h>

int main(void){

  long x,y,l,m;
  std::cin >> x;
/*  
  m=abs(x)/l+abs(y)/l;
  
  if(x<0) m++;
  if(y<0) m++;
  if(x>0) m++;
  if(abs(x)%l) m++;
  if(abs(y)%l) m++;
  if(x==0 && y<0) m++;
*/
  std::cout << (x*15)/10 <<std::endl;
}