#include <fstream.h>
int main ()
{ int v[1001],y,nr,n,z,i,j,x,nrf;
ifstream f("fractii.in");
ofstream g("fractii.out");
f>>n;
v[1]=1;
v[2]=1;
x=2;
y=2;
nr=0;
v[3]=2;
for (i=5;i<=n;i++)
  if (i%2==1) v[i]=v[i-2]+2;
j=4;
while (j<=n)
  { z=y;
   while (y>0)
     {
     v[j]=x;
     j+=2;
     y--;
  }
x+=2;
z++;
y=z;
}
int k;
nrf=1;
for (k=2;k<=n;k++)
  nrf+=2*v[k];
g<<nrf;
f.close();
g.close();
return 0;
}