N = int(input())
line = list(map(int, input().split(' ')))
def find_where(Line, num, M):
    for i in range(M):
        if Line[i] == num:
            return i
    return -1

result = N
index = N
for i in range(N):
    index = find_where(line, N-i, index)
    if index != -1:
        result -= 1
    else:
        break

print(result)