n = int(input())
step = 0
train = [int(x) for x in input().split()]

index = n - 1
exchange = True
while index > 0 and exchange:
    exchange = False
    for i in range(index):
        if train[i] > train[i+1]:
            exchange = True
            step += 1
            train[i],train[i+1] = train[i+1],train[i]
    index -= 1
print(step)