import math
def solution(n):
res = [[0] * n for _ in range(n)]
row,col = -1,0
curNum=1
for i in range(n):
for j in range(i,n):
if i%3==0:
row+=1
elif i%3==1:
col+=1
else:
row-=1
col-=1
res[row][col]=curNum
curNum+=1
arr=[]
for i in range(n):
for j in range(n):
if res[i][j]!=0:
arr.append(res[i][j])
return arr