Snake Grid

import sys
n = sys.stdin.read()#Take input of one number
n = int(n)
matrix = [] #This is a empty matrix we will use later to add stuff to
for i in range(n):
    matrix.append([])
    for j in range(n):
        matrix[i].append([])#Fill the matrix with empty indexs. If this were java I wouldn't have had to do this
order = []#This will become a list of where the numbers go. For example, the first thing in here will be 0,0 because 1 goes in spot 0,0
for i in range(2*n+1):#Loop for 2n, so i can reach the last spot in the grid
    temp = []
    for y in range(i, -1, -1):#This chooses where y starts off
        x = y-i
        if abs(y) > n-1 or abs(x) > n-1:
            continue
        temp.append([abs(y),abs(x)])#Add the location
    if i % 2 == 0:
        temp.sort(reverse = True)#we want to go down on even
    else:
        temp.sort(reverse = False)#and up on odds
    for j in range(len(temp)):#Add the indexs to order.
        order.append(temp[j])
for i in range(len(order)):#Assemble Order inside Matrix
    matrix[order[i][0]][order[i][1]] = str(i+1)
for i in range(len(matrix)):#Print matrix
    print(" ".join(matrix[i]))