class fenwick_tree:
    def __init__(self, n):
        self.n = n
        #x, a1, a2, ..., an
        self.arr = [0] * (n+1)
    
    def add(self, i, x): #1_indexed
        while i <= self.n:
            self.arr[i] += x
            i += i & -i
    
    def query(self, i): #a1 + a2 + ... + ai
        res = 0
        while i > 0:
            res += self.arr[i]
            i -= i & -i
        return res

N = int(input())
M = [int(input()) for _ in range(N)]
ft = fenwick_tree(N)
ans = 0

for i in range(N):
    ans += i - ft.query(M[i]-1)
    ft.add(M[i], 1)

print(ans)