import sys
input = sys.stdin.readline

N = int(input())
P = list(map(int, input().split()))
idx = [-1]*(N+1)

for i in range(N):
    idx[P[i]] = i
    
ans = 0

for i in range(N):
    while P[i]>i+1:
        x, y = i, idx[P[i]-1]
        idx[P[i]] = y
        P[x], P[y] = P[y], P[x]
        ans += 1

print(ans)