val n = valOf (TextIO.scanStream (LargeInt.scan StringCvt.DEC) TextIO.stdIn);

val k = n div 3;

val s1 = k * (k + 1) div 2;

val a1 = if 3*k+1 = n then n else 0;
val a2 = if 3*k+2 = n then n*(n+1)-1 else 0;
val a3 = (27*s1+3*(2*k+1)-3)*s1-k;

print (LargeInt.toString (a1+a2+a3) ^ "\n");