x=int(input()) s=0 d=0 if 1<=x<=104: for i in range(1,x): while d<x: d+=i b=i break h=d-x if h==0: for i in range(1,b+1): s+=i2 print(s) else: for i in range(1,b+1): s+=i**2 s-=h*b print(s)