#include <stdio.h>
FILE *fin, *fout;

int fractired (long int n )
{ int i,j,nr=0;

 for(i=1;i<=n;i++)
 {for(j=1;j<=n;j++)
   {
                   if(i%2==0&& j%2==0)
                    j++;
                   if(i==j)
                    j++; 
      nr++; }
      }
      return nr;
      }
int main()
{long int n;
    fin=fopen("fractii.in" , "r");
    fout=fopen("fractii.out", "w");
    fscanf(fin, "%d", &n);
    fprintf(fout, "%d", fractired(n));
    fclose(fin);
    fclose(fout);
}