a=int(input())

def tri_num(n):
    tri = set()
    for i in range(1,n-1):
        for j in range(i,n-1):
            for k in range(j,n-1):
                if i+j>k and i+k>j and j+k>i and i+j+k==n:
                    tri.add(tuple(sorted([i,j,n-i-j])))
    return len(tri)

print(tri_num(a))