N=int(input())
A=list(map(int, input().split()))
class Bit:
    def __init__(self, n):
        self.size = n
        self.tree = [0] * (n + 1)
  
    def sum(self, i):
        s = 0
        while i > 0:
            s += self.tree[i]
            i -= i & -i
        return s
  
    def add(self, i, x):
        while i <= self.size:
            self.tree[i] += x
            i += i & -i
 
ppp=A
bit=Bit(5001)
ans=0
 
for i, p in enumerate(ppp):
  bit.add(p, 1)
  ans += i + 1 - bit.sum(p)
 
print(ans)