# a=int(input())
# for i in range(a):
# print(' '*(a-1-i),end='*')
# print(' ' (i2), end='*\n')
# for i in range(a-1,-1,-1):
# print(' ' (a-1-i), end='')
# print(' ' (i 2), end='*\n')
# a,b=map(int,input().split())
# for i in range(b):
# for j in range(a):
# if i==0 and j==0 or i==b-1 and j==a-1 or j==a-1 and i==0 or j==0 and i==b-1:
# print('+',end='')
# else:
# if i!=0 and i!=b-1 and j!=0 and j!=a-1:
# print(' ',end='')
# elif i and i!=b-1:
# print('|', end='')
# else:
# print('-',end='')
# print('\n',end='')
a=int(input())
s=0
k=0
for i in range(1,a):
x=[]