n = int(input())
a = [int(i) for i in input().split()]

n1 = 0
n2 = 0

for i in range(n):
    if a[i] == 1:
        n1 += 1
    elif a[i] == 2:
        n2 += 1
        
ans = 0

ans += 1*(n-n1)*(n-n1-1)//2#両方2以上
ans += 2*n1*((n-n2-1)+(n-n2-n1))//2#
ans += 3*(n1)*n2

#print((n-n2-1),"n-n2-1")

print(ans)