import sys

sys.setrecursionlimit(10 ** 6)
from bisect import *
from collections import *
from heapq import *

def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def SI(): return sys.stdin.readline()[:-1]
def LLI(rows_number): return [LI() for _ in range(rows_number)]
int1 = lambda x: int(x) - 1
def MI1(): return map(int1, sys.stdin.readline().split())
def LI1(): return list(map(int1, sys.stdin.readline().split()))
p2D = lambda x: print(*x, sep="\n")
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

class BIT:
    def __init__(self, n):
        n += 5
        self.aa = [0] * n
        self.n = n

    def add(self, i, a):
        i += 1
        while i < self.n:
            self.aa[i] += a
            i += i & -i

    def sum(self, i):
        i += 1
        res = 0
        while i > 0:
            res += self.aa[i]
            i -= i & -i
        return res

def main():
    n = II()
    bit=BIT(n)
    ans=0
    for i in range(n):
        m=II()
        ans+=i-bit.sum(m)
        bit.add(m,1)
    print(ans)

main()