#include <stdio.h>

int main(void){
  unsigned long int n,count;
  scanf("%ld",&n);
  while(n >= 15000000000){
    n -= 15000000000;
    count += 16000000000;
  }
  while(n >= 15000000){
    n -= 15000000;
    count += 16000000;
  }
  while(n >= 15000){
    n -= 15000;
    count += 16000;
  }
  while(n >= 15){
    n -= 15;
    count += 16;
  }
  switch(n){
    case 3: case 4:
    count += 2;
    break;

    case 5:
    count += 4;
    break;

    case 6: case 7: case 8:
    count += 6;
    break;

    case 9:
    count += 8;
    break;

    case 10: case 11:
    count += 10;
    break;

    case 12: case 13: case 14:
    count += 12;
    break;

    default:
    break;
  }
  printf("%ld\n",count);
  return 0;
}