#Медленный способ
file = open('8A.txt')
A = list(map(int, file.readlines()))
n = A[0]
A = A[1:]
count = 0
for i in range(n):
     for j in range(i + 1, n):
          if (A[i] + A[j]) % 80 == 0 and (A[i] > 50000 or A[j] > 50000):
               count += 1
print(count)

#Статический способ
file = open('8B.txt')
A = list(map(int, file.readlines()))
n = A[0]
A = A[1:]
kb = [0] * 80
k = [0] * 80
for i in range(n):
     ost = A[i] % 80
     if A[i] > 50000:
          kb[ost] += 1
     else:
          k[ost] += 1
count = (k[0] * kb[0]) + (kb[0] * (kb[0] - 1) // 2) + (k[40] * kb[40]) + (kb[40] * (kb[40] - 1) // 2)
for i in range(1, 40):
     count += (kb[i] * kb[80 - i]) + (k[i] * kb[80 - i]) + (kb[i] * k[80 - i])
print(count)

#Динамичсекий способ
file = open('8B.txt')
A = list(map(int, file.readlines()))
n = A[0]
A = A[1:]
kb = [0] * 80
k = [0] * 80
count = 0
for i in range(n):
     ost = A[i] % 80
     if A[i] > 50000:
          count += kb[(80 - ost % 80) % 80] + k[(80 - ost % 80) % 80]
          kb[ost] += 1
     else:
          count += kb[(80 - ost % 80) % 80]
          k[ost] += 1
print(count)