N = int(input())
A = list(map(int, input().split())) 
TEN = [[0] * 10 for i in range(N+1)]
for i in range(N):
    a = A[i]%10
    for j in range(10):
        if TEN[i][j]!=0 or j==0:
            TEN[i+1][(j+a)%10] = max(TEN[i+1][(j+a)%10] ,TEN[i][j]+1)
            print('aaaa')
        else:
            TEN[i+1][(j+a)%10] = TEN[i][(j+a)%10]
 
print(TEN[N][0])