N = int(input())
A = list(map(int, input().split()))
isok = [False]*N
num = N
for i in reversed(range(N)):
    if A[i] == num:
        isok[num-1] = True
        num -= 1

res = 0
for i in reversed(range(N)):
    if isok[i]:
        res += 1
    else:
        print(N-res)
        exit()
print(N-res)