#=================================================
N=int(input())
P=[0]+list(map(int,input().split()))
P_inv=[0]*(N+1)

for i in range(N+1):
    P_inv[P[i]]=i

X=0
for i in range(N+1):
    while P[i]!=i:
        X+=1
        j=P_inv[P[i]-1]
        a=P[i]; b=P[j]
        P[i],P[j]=P[j],P[i]
        P_inv[a], P_inv[b]=j,i

print(X)