N = int(input())
src = []
for i in range(N):
    a = int(input())
    src.append(a)

bit = [0] * (N+1)
def bit_add(a,w):
    x = a
    while x <= N:
        bit[x] += w
        x += (x & -x)
 
def bit_sum(a):
    x = a
    ret = 0
    while x > 0:
        ret += bit[x]
        x -= (x & -x)
    return ret
 
ans = 0
for i in range(N-1,-1,-1):
    a = src[i]
    ans += bit_sum(a)
    bit_add(a,1)

print(ans)