class Bit:
    def __init__(self, n):
        self.size = n
        self.n0 = 1 << (n.bit_length() - 1)
        self.tree = [0] * (n + 1)
    
    def range_sum(self, l, r):
        return self.sum(r - 1) - self.sum(l - 1)
        
    def sum(self, i):
        i += 1
        s = 0
        while i > 0:
            s += self.tree[i]
            i -= i & -i
        return s
        
    def get(self, i):
        return self.sum(i) - self.sum(i - 1)
 
    def add(self, i, x):
        i += 1
        while i <= self.size:
            self.tree[i] += x
            i += i & -i
         
    def lower_bound(self, x):
        pos = 0
        plus = self.n0
        while plus > 0:
            if pos + plus <= self.size and self.tree[pos + plus] < x:
                x -= self.tree[pos + plus]
                pos += plus
            plus //= 2
        return pos

n = int(input())
A = [int(input()) for _ in range(n)]
bit = Bit(n + 1)
ans = 0
for a in A:
    ans += bit.range_sum(a, n + 1)
    bit.add(a, 1)
print(ans)