N = int(input())
P = list(map(int,input().split()))
cnt = 0
Q = [0 for _ in range(N+1)]
for index,p in enumerate(P):
    Q[p] = index
flag = True
j = 1
while flag:
    flag = False
    if Q[j] == j -1:
        j += 1 
    for i in range(j,N): 
        if Q[i] > Q[i+1]:
            Q[i],Q[i+1] = Q[i+1],Q[i]
            flag = True
            cnt += 1
            break
print(cnt)