Problem:


Score : 400 points

Problem Statement

We have N bricks arranged in a row from left to right.

The i-th brick from the left (1 \leq i \leq N) has an integer a_i written on it.

Among them, you can break at most N-1 bricks of your choice.

Let us say there are K bricks remaining. Snuke will be satisfied if, for each integer i (1 \leq i \leq K), the i-th of those brick from the left has the integer i written on it.

Find the minimum number of bricks you need to break to satisfy Snuke's desire. If his desire is unsatisfiable, print -1 instead.

Constraints

All values in input are integers.

1 \leq N \leq 200000

1 \leq a_i \leq N

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the minimum number of bricks that need to be broken to satisfy Snuke's desire, or print -1 if his desire is unsatisfiable.

Sample Input 1

3
2 1 2

Sample Output 1

1

If we break the leftmost brick, the remaining bricks have integers 1 and 2 written on them from left to right, in which case Snuke will be satisfied.

Sample Input 2

3
2 2 2

Sample Output 2

-1

In this case, there is no way to break some of the bricks to satisfy Snuke's desire.

Sample Input 3

10
3 1 4 1 5 9 2 6 5 3

Sample Output 3

7

Sample Input 4

1
1

Sample Output 4

0

There may be no need to break the bricks at all.



Sample input:
3
2 1 2


Sample output:
1

Submission status: Accepted

Solution code:
n = int(input())
l = list(map(int, input().split()))

sum = 0
counter = 1
left = 0

for i in range(left, n):
    if l[i] == counter:
        sum += i-left
        counter += 1
        left = i+1
        continue
sum += n-left

if counter == 1:
    print(-1)
else:
    print(sum)

Submission status: Accepted

Solution code:
# coding: utf-8

from collections import deque

N = int(input())
array = deque(list(map(int, input().split())))
ans, tmp, ctr = 0, 0, 1

for i in range(N):
    tmp = array.popleft()
    if tmp == ctr:
        ctr += 1
    else:
        ans += 1

if ctr > 1:
    print(ans)
else:
    print(-1)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int,input().split()))
b = 0
for i in range(n):
  if a[i] == b+1:
    b = a[i]
print(n-b if b>0 else -1)

Submission status: Accepted

Solution code:
import sys
input = sys.stdin.buffer.readline

def main():
	N=int(input())
	vA=list(map(int, input().split()))

	p = 0
	res = 0
	for a in vA:
		if p+1 == a:
			p += 1
		else:
			res += 1

	print(res if p else -1)

main()

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))

i = 1
for x in a:
    if x == i:
        i += 1

if i == 1:
    print(-1)
else:
    print(n - i + 1)

Submission status: Accepted

Solution code:
def main():
    N = int(input())
    A = list(map(int, input().split()))
    cnt = 0
    for a in A:
        if a == cnt + 1:
            cnt += 1
    if cnt == 0:
        print(-1)
    else:
        print(N-cnt)


if __name__ == "__main__":
    main()

Submission status: Accepted

Solution code:
N=int(input())
a=map(int, input().split())
a=list(a)
count = 1
ans = 0;
for i in range(N):
  if a[i] == count:
    count+=1 
  else:
    ans+=1
print("-1" if ans == N else ans)

Submission status: Accepted

Solution code:

N=int(input())
A=input()
a=1
for i in A.split():
    if int(i)==a:
        a+=1
if a==1:
    print(-1)
else:
    print(N-a + 1)

Submission status: Accepted

Solution code:
N = int(input())
li_str = input().split()
li_int = []
for i in li_str:
    li_int.append(int(i))
count= 1
num =  N + 1
for i in li_int:
    if i == count:
        num = count
        count += 1
print(N - num)

Submission status: Accepted

Solution code:
N=int(input())
a=[int(i) for i in input().split()]
k=0
for i in range(N):
    if a[i]==k+1:
        k+=1
if k!=0:
    print(N-k)
else:
    print(-1)

Submission status: Accepted

Solution code:
N =  int(input())
arr = [int(n) for n in input().split(' ')]

j = 0

i = 1
for tmp in arr:
    if i != tmp:
        j = j + 1
    else :
        i = i + 1
else:
    if j == len(arr):
        j = -1

print(j)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))

cnt = 0
pointer = 1

for i in range(n):
    if a[i] == pointer:
        pointer += 1
    else:
        cnt += 1
if pointer == 1:
    print(-1)
else:
    print(cnt)

Submission status: Accepted

Solution code:
N = int(input())
a = [i for i in map(int, input().split())]
     
num = 0
for i in range(N):
  if a[i] == (num + 1):
    num += 1
    
if num == 0:
  print(-1)
else:
  print(N-num)

Submission status: Accepted

Solution code:
N = int(input())
A = list(map(int, input().split()))

c = 0
e = len(A)
d = 1
for i in range(e):
  if A[i] == d:
    d = d + 1
  else:
    c = c + 1

if c == e:
    print(-1)
else:
    print(c)

Submission status: Accepted

Solution code:
n = int(input())
tmp = input().split(" ")
x = list()
for i in tmp:
  x.append(int(i))
c=0
for i in x:
  if i==(c+1):
    c+=1
br = n-c

if c==0:
  print("-1")
else:
  print(br)

Submission status: Accepted

Solution code:
n = int(input())
A = list(map(int, input().split()))

ans = 0
break_tgt = 1

for i in range(n):
    if A[i] == break_tgt:
        break_tgt += 1
    else:
        ans += 1

if ans == n:
    ans = -1

print(ans)

Submission status: Accepted

Solution code:
N = int(input())
A = list(map(int, input().split()))
num = 1
ctr = 0

for a in A:
	if a == num:
		num += 1
	else:
		ctr += 1
if num == 1:
	print(-1)
else:
	print(ctr)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))
ans = 0
st = 1

for i in range(n):
    if st == a[i]:
        st += 1
    else:
        ans += 1

if n == ans:
    ans = -1

print(ans)

Submission status: Accepted

Solution code:
def getdata_input():
    while True:
        yield input()

it=getdata_input()
N=int(next(it))
arr=[-1]*N
arr[0],*arr[1:]=map(int,next(it).split())
n=1
out=[]
i=-1
while True:
    try:
        i=arr.index(n,i+1)
        out.append(i)
        n+=1
    except ValueError:
        if i<N-1 and n>1 :
            out.append(N)
        break
if len(out) ==0: 
    print(-1)
else:
    i,j=0,0
    total=0
    for x in out:
        j=x
        total+=(j-i)
        i=j+1
        
    print(total)

Submission status: Accepted

Solution code:
n=int(input())
S=input().split()

s=list(S)

for i in range(n):
    s[i]=int(s[i])
#print(s)

def ikeruka(s):
    sum=0
    for i in range(len(s)):
        if s[i]==1:
            sum+=1

    if sum>=1:
        return True
    else:
        return False

#print(ikeruka(s))

if ikeruka(s):

    #j  blocknumber
    #l
    j=0
    l=1
    while j<=n-1:
        if s[j]==l:
            l+=1
            j+=1

            if j>n:
                break
            
        else:
            j+=1

    print(n-l+1)

else:
    print(-1)

Submission status: Accepted

Solution code:
N = int(input())
al = list(map(int,input().split()))
target = 1
ans = 0
for a in al:
    if a == target:
        target += 1
    else:
        ans += 1
if ans == N:
    print(-1)
else:
    print(ans)

Submission status: Accepted

Solution code:
n=int(input())
h=list(map(int,input().split()))
mn=min(h)
cnt=0
if(mn!=1):
    print("-1")
    exit()
i=1
for k in h:
    if(k==i):
        i=i+1
    else:
        cnt=cnt+1
print(cnt)

Submission status: Accepted

Solution code:
N = int(input())
a = list(map(int, input().split()))

tmp = 1
count = 0
for b in a:
    if tmp == b:
        count += 1
        tmp += 1

print(-1 if count == 0 else N-count)

Submission status: Accepted

Solution code:
import sys

def main():
    N = int(input())
    a = list(map(int,input().split()))
    num = 1

    for i in a:
        if(i==num):
            num += 1

    if(num!=1):
        print(len(a) - num + 1)
    else:
        print('-1')

main()

Submission status: Accepted

Solution code:
n = int(input())
array = list(map(int, input().split()))

bt = 0 #break times
i = 0  
j = 0  #iterator

while i < n:
  while j < n:
    if array[j] == i+1:
      bt += 1
      break
      
    else:
      if j == n-1:
        if i == 0:
          bt = -1
          i = n+1
          j = n+1
          break
        else:
          i = n+1
          j = n+1
          break
          
    j += 1
  i +=1
  
if bt != -1:
  bt = n - bt
  
print(bt)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))
i = 1
broken = 0
found = False
for v in a:
    if i == v:
        i += 1
        found = True
    else:
        broken += 1

if found:
    print(broken)
else:
    print(-1)

Submission status: Accepted

Solution code:
import sys
input = sys.stdin.readline
N = int(input())
li_A = list(map(int, input().split()))
count = 0
find = 1
for i in range(N):
    if li_A[i] == find:
        find += 1
    else:
        count += 1
if count < N:
    print(count)
else:
    print("-1")

Submission status: Accepted

Solution code:
N = int(input())
A = list(map(int, input().split()))

ans = 0
now = 1
for a in A:
    if a == now:
        now += 1
    else:
        ans += 1

if now == 1:
    print(-1)
else:
    print(ans)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))
ans = 0
i = 0
while i + 1 <= len(a):
    #index+1がリストの要素と違ったら
    if a[i] != i + 1:
        #正しい要素があるか確認
        if i + 1 in a:
            #正しい要素の手前まで削除
            del a[i:a.index(i + 1)]
        #正しい要素がないなら全部削除
        else:
            del a[i:]
        
    #index+1がリストの要素と同じなら次の要素へ
    else:
        i += 1
#全部消しちゃったら不可能
if len(a) == 0:
  print(-1)
#残ってる要素を引いたら壊した数になる
else:
    print(n - len(a))

Submission status: Accepted

Solution code:
a=int(input())
lis=list(map(int,input().split()))
suu=0
ans=0
x=0
while len(lis)>x:
  if lis[x]==suu+1:
    suu+=1
  else:
    ans+=1
  x+=1
if ans==a:
  print(-1)
else:
  print(ans)

Submission status: Accepted

Solution code:
N = int(input())
a = list(map(int, input().split()))

num = 1
for i in range(len(a)):
    if a[i]==num:
        num += 1
if num==1:
    ans = -1
else:
    ans = N - num + 1
print(ans)

Submission status: Accepted

Solution code:
# データ読み込み

import sys
from collections import deque

def input_data(d=""):
  t = sys.stdin.read()
  if t:
    return t
  else:
    if d[0] == "\n":
      d = d[1:]
    if d[-1] == "\n":
      d = d[:-1]    
    return d

A, *B  = map(int,input_data().split())

m = []

if 1 not in B:
  print(-1)
else:
  out = 0
  c = 1
  for i in B:
    if i == c:
      c+=1
    else:
      out+=1
  print(out)

Submission status: Accepted

Solution code:
N=int(input())
A=list(map(int,input().split()))

i=0;j=0
while(i<N):
    if A[i]==j+1:
        j+=1
    i+=1

print(N-j if j!=0 else -1)

Submission status: Accepted

Solution code:
import sys

input = sys.stdin.readline


class AtCoder:
    def main(self):
        N = int(input())
        a = list(map(int, input().split()))

        broken = 0
        next_target = 1
        for i in range(N):
            if a[i] != next_target:
                broken += 1
            else:
                next_target += 1

        if broken < N:
            print(broken)
        else:
            print(-1)


# Run main
if __name__ == '__main__':
    AtCoder().main()

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))
c = 1
for i in range(n):
    if a[i] == c:
        c += 1
if c == 1:
    print(-1)
else:
    print(n - c + 1)

Submission status: Accepted

Solution code:
def main(sample_file = ''):

    """ convenient functions
    # for i, a in enumerate(iterable)
    # q, mod = divmod(a, b)
    # divmod(x, y) returns the tuple (x//y, x%y)
    # Higher-order function: reduce(operator.mul, xyz_count, 1)
    # manage median(s) using two heapq https://atcoder.jp/contests/abc127/tasks/abc127_f
    """

    """convenient decorator
    # @functools.lru_cache():
    # to facilitate use of recursive function
        # ex:
        # from functools import lru_cache
        # import sys
        # sys.setrecursionlimit(10**9)
        # @lru_cache(maxsize=None)
        # def fib(n):
        #     if n < 2:
        #         return n
        #     return fib(n-1) + fib(n-2)
        # print(fib(1000))
    """
    
    # import numpy as np
    import sys
    sys.setrecursionlimit(10**7)
    from itertools import accumulate, combinations, permutations, product # https://docs.python.org/ja/3/library/itertools.html
    # accumulate() returns iterator! to get list: list(accumulate())
    from math import factorial, ceil, floor, sqrt
    def factorize(n):
        """return the factors of the Arg and count of each factor
        
        Args:
            n (long): number to be resolved into factors
        
        Returns:
            list of tuples: factorize(220) returns [(2, 2), (5, 1), (11, 1)]
        """
        fct = []  # prime factor
        b, e = 2, 0  # base, exponent
        while b * b <= n:
            while n % b == 0:
                n = n // b
                e = e + 1
            if e > 0:
                fct.append((b, e))
            b, e = b + 1, 0
        if n > 1:
            fct.append((n, 1))
        return fct
    def combinations_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        # TODO: How should I do when n - r is negative?
        if n < 0 or r < 0:
            raise Exception('combinations_count(n, r) not defined when n or r is negative')
        if n - r < r: r = n - r
        if r < 0: return 0
        if r == 0: return 1
        if r == 1: return n
        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]
        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot
        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
        return result
    def combinations_with_replacement_count(n, r):
        """Return the number of selecting r pieces of items from n kinds of items allowing individual elements to be repeated more than once.
        
        Args:
            n (long): number
            r (long): number
        
        Raises:
            Exception: not defined when n or r is negative
        
        Returns:
            long: number
        """
        if n < 0 or r < 0:
            raise Exception('combinations_with_replacement_count(n, r) not defined when n or r is negative')
        elif n == 0:
            return 1
        else:
            return combinations_count(n + r - 1, r)
    from bisect import bisect_left, bisect_right
    from collections import deque, Counter, defaultdict # https://docs.python.org/ja/3/library/collections.html#collections.deque
    from heapq import heapify, heappop, heappush, heappushpop, heapreplace,nlargest,nsmallest # https://docs.python.org/ja/3/library/heapq.html
    from copy import deepcopy, copy # https://docs.python.org/ja/3/library/copy.html
    import operator
    from operator import itemgetter #sort 
    # ex1: List.sort(key=itemgetter(1))
    # ex2: sorted(tuples, key=itemgetter(1,2))
    from functools import reduce, lru_cache
    def chmin(x, y):
        """change minimum
        if x > y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current minimum value
            y (long): potential minimum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x > y:
            x = y
            return (x, True)
        else:
            return (x, False)
    def chmax(x, y):
        """change maximum
        if x < y, x = y and return (x, True).
        convenient when solving problems of dp[i]
        
        Args:
            x (long): current maximum value
            y (long): potential maximum value
        
        Returns:
            (x, bool): (x, True) when updated, else (x, False)
        """
        if x < y:
            x = y
            return (x, True)
        else:
            return (x, False)

    from fractions import gcd # Deprecated since version 3.5: Use math.gcd() instead.
    def gcds(numbers):
        return reduce(gcd, numbers)
    def lcm(x, y):
        return (x * y) // gcd(x, y)
    def lcms(numbers):
        return reduce(lcm, numbers, 1)
    def make_divisors(n, reversed=False):
        """create list of divisors
        
        Args:
            number (int): number from which list of divisors is created
            reversed (bool, optional): ascending order if False. Defaults to False.
        
        Returns:
            list: list of divisors
        """
        divisors = set()
        for i in range(1, int(n**0.5)+1):
            if n % i == 0:
                divisors.add(i)
                divisors.add(n//i)
        return sorted(list(divisors),reverse=reversed)
    
    # first create factorial_list
    # fac_list = mod_factorial_list(n)
    INF = 10 ** 18
    MOD = 10 ** 9 + 7
    modpow = lambda a, n, p = MOD: pow(a, n, p) # Recursive function in python is slow!
    def modinv(a, p = MOD):
        # evaluate reciprocal using Fermat's little theorem:
        # a**(p-1) is identical to 1 (mod p) when a and p is coprime
        return modpow(a, p-2, p)
    def modinv_list(n, p = MOD):
        if n <= 1:
            return [0,1][:n+1]
        else:
            inv_t = [0,1]
            for i in range(2, n+1):
                inv_t += [inv_t[p % i] * (p - int(p / i)) % p]
            return inv_t
    def modfactorial_list(n, p = MOD):
        if n == 0:
            return [1]
        else:
            l = [0] * (n+1)
            tmp = 1
            for i in range(1, n+1):
                tmp = tmp * i % p
                l[i] = tmp
            return l
    def modcomb(n, k, fac_list = [], p = MOD):
        # fac_list = modfactorial_list(100)
        # print(modcomb(100, 5, modfactorial_list(100)))
        from math import factorial
        if n < 0 or k < 0 or n < k: return 0
        if n == 0 or k == 0: return 1
        if len(fac_list) <= n:
            a = factorial(n) % p
            b = factorial(k) % p
            c = factorial(n-k) % p
        else:
            a = fac_list[n]
            b = fac_list[k]
            c = fac_list[n-k]
        return (a * modpow(b, p-2, p) * modpow(c, p-2, p)) % p
    def modadd(a, b, p = MOD):
        return (a + b) % MOD
    def modsub(a, b, p = MOD):
        return (a - b) % p
    def modmul(a, b, p = MOD):
        return ((a % p) * (b % p)) % p
    def moddiv(a, b, p = MOD):
        return modmul(a, modpow(b, p-2, p))

    class UnionFindTree:
        """union find tree class
        TODO: fix this description...
        how to use (example):
        >>  uf = UnionFindTree(N) 
        >>  if uf.find_root(a) == uf.find_root(b):
        >>      do something
        >>  else:
        >>      do something
        >>      uf.unite(a, b)
        """
        def __init__(self, N):
            self.root = [-1] * (N+1)
            self.rank   = [0]  * (N+1)
            self.connected_num = [1] * (N+1)
    
        def find_root(self,x):
            root = self.root
            while root[x] != -1:
                x = root[x]
            return x
    
        def unite(self,x,y):
            root = self.root
            rank = self.rank
            connected_num = self.connected_num
            find_root = self.find_root
    
            rx = find_root(x)
            ry = find_root(y)
            if rx != ry:
                if rank[rx] < rank[ry]:
                    root[rx] = ry
                    rx,ry = ry,rx
                else:
                    if rank[rx] == rank[ry]:
                        rank[rx] += 1
                    root[ry] = rx       
                connected_num[rx] += connected_num[ry]

    # Graph: https://en.wikipedia.org/wiki/Directed_graph
    # Bellman-Ford: O(|V||E|). Use this if there exists an edge with negative length in the graph
    # After N steps, the shortest path has converded if there doesn't exist an cycle of edges with negative
    # Watch out: d[N] == d[2*N] doesn't necessarily mean the graph doesn't have negative cycle
    # ref: https://www.youtube.com/watch?v=1Z6ofKN03_Y

    def BellmanFord(N, M, ABC, vertex_start, vertex_end, value_if_inf = -1, find_shortest = False):
        """to calculate furthest or shortest length between vertex_start and vertex_end using BellmanFord algorithm
        
        Args:
            N (int): number of vertices
            M (int): number of edges
            ABC (list): [(ai, bi, ci) for _ in range(N)] where i-th edge is directed from vertex ai to vertex bi and the length is ci 
            vertex_start (int): start vertex. usually use 0.
            vertex_end (int): end vertex. usually use N-1.
            value_if_inf (int or string as you like, optional): value you want when the furthest (or shortest) distance is infinite (or -infinite). Defaults to -1.
            find_shortest (bool, optional): choose False to find furthest path. Defaults to False.
        
        Returns:
            int or string: normally int (but can be str if you set value_if_inf to str)
            
        Example:
                N, M, P = R()
                ABC = [R() for _ in range(M)]
                ABC = [(a-1, b-1, c-P) for a, b, c in ABC]
                print(BellmanFord(N, M, ABC, 0, N-1, value_if_inf = 'inf'))

        """

        def make_reachable_list(N, M, ABC, vertex_start, vertex_end):
            reachable_to_direct = defaultdict(list)
            reachable_from_direct = defaultdict(list)
            reachable_from_start = [False] * N
            reachable_to_end = [False] * N
            reachable_from_start[vertex_start] = True
            reachable_to_end[vertex_end] = True
            reachable_from_both_sides = [False] * N
            dfs_from_start = []
            dfs_to_end = []
            for a, b, c in ABC:
                reachable_to_direct[a].append(b)
                reachable_from_direct[b].append(a)
                if a == vertex_start:
                    dfs_from_start.append(b)
                    reachable_from_start[b] = True
                if b == vertex_end:
                    dfs_to_end.append(a)
                    reachable_to_end[a] = True
            while dfs_from_start:
                v = dfs_from_start.pop()
                for i in reachable_to_direct[v]:
                    if not reachable_from_start[i]:
                        reachable_from_start[i] = True
                        dfs_from_start.append(i)
            while dfs_to_end:
                v = dfs_to_end.pop()
                for i in reachable_from_direct[v]:
                    if not reachable_to_end[i]:
                        reachable_to_end[i] = True
                        dfs_to_end.append(i)
            for i in range(N):
                reachable_from_both_sides[i] = reachable_from_start[i] and reachable_to_end[i]
            return reachable_from_both_sides
        
        reachable_from_both_sides = make_reachable_list(N, M, ABC, vertex_start, vertex_end)
        
        if find_shortest:
            dist = [INF for i in range(N)]
        else:
            dist = [-INF for i in range(N)]
        
        dist[vertex_start] = 0
        for i in range(N):
            updated = False
            for a, b, c in ABC:
                if not reachable_from_both_sides[a]:
                    continue
                elif find_shortest:
                    update_condition = dist[a] + c < dist[b]
                else:
                    update_condition = dist[a] + c > dist[b]
                if dist[a] != INF and update_condition:
                    dist[b] = dist[a] + c
                    updated = True
                    if i == N-1:
                        return value_if_inf
            if not updated:
                break
        return dist[vertex_end]

    """ initialize variables and set inputs
    # initialize variables
        # to initialize list, use [0] * n
        # to initialize two dimentional array:
            # ex) [[0] * N for _ in range(N)]
            # ex2) dp = [[0] * (N+1) for _ in range(W*2)]
    # set inputs
        # put inputs between specific values (almost as quickly)
        # ex) S = [-INF] + [int(r()) for _ in range(A)] + [INF]
        # open(0).read() is sometimes useful:
        # ex) n, m, *x = map(int, open(0).read().split())
        #     min(x[::2]) - max(x[1::2])
        # ex2) *x, = map(int, open(0).read().split())
        #     don't forget to add comma after *x if only one variable is used
    # preprocessing
        # transpose = [x for x in zip(*data)]
        # ex) [[1, 2, 3], [4, 5, 6], [7, 8, 9]] => [(1, 4, 7), (2, 5, 8), (3, 6, 9)]
        # flat = [flatten for inner in data for flatten in inner]
        # ex) [[1, 2, 3], [4, 5, 6], [7, 8, 9]] => [1, 2, 3, 4, 5, 6, 7, 8, 9]
    # calculate and output
        # output pattern
        # ex1) print(*l) => when l = [2, 5, 6], printed 2 5 6
    """

    # functions to read input
    r = lambda: sys.stdin.readline().strip()
    r_int = lambda: int(r())
    r_float = lambda: float(r())
    R = lambda: list(map(int, r().split()))
    R_str = lambda: r().split()
    R_map = lambda: map(int, r().split())
    R_float = lambda: list(map(float, r().split()))
    R_tuple = lambda: tuple(map(int, r().split()))

    """ how to treat input
    # single int: int(r())
    # single string: r()
    # single float: float(r())
    # line int: R()
    # line string: r().split()
    # line (str, int, int): [j if i == 0 else int(j) for i, j in enumerate(r().split())]
    # lines int: [R() for _ in range(n)]
    """

    # for test
    if sample_file:
        sys.stdin = open(sample_file)
        
    # ----------------------------------
    # main

    N = r_int()
    A = R()
    tmp = 0
    for a in A:
        if a == tmp+1:
            tmp += 1
    if tmp == 0:
        print(-1)
    else:
        print(N-tmp)
    
    # to finish code, use return instead of exit()
    # end of main
    # ----------------------------------

    """memo: how to use defaultdict of list
    # initialize
    Dic = defaultdict(list)
    # append / extend
    Dic[x].append(y)
    # three methods for loop: keys(), values(), items()
    for k, v in Dic.items():
    """
    
    """memo: how to solve binary problems
    # to make binary digits text
    >>> a = 5
    >>> bin_str_a = format(a, '#06b')
    >>> print(bin_str_a)
    0b0101 # first 2 strings (='0b') indicates it is binary
    """
    
    """memo: how to solve the problem
    creating simple test/answer
    greed
    simple dp
    graph
    """

if __name__ == '__main__':
    main()

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int,input().split()))

hit = 0
kazu = 1
for i in a:
    if i == kazu:
        hit += 1
        kazu += 1

if hit == 0:
    print(-1)
else:
    print(n - hit)

Submission status: Accepted

Solution code:
N = int(input())
A = [int(i) for i in input().split()]
sum = 0
for i in range(N):
    if sum + 1 == A[i]:
        sum = sum + 1
if sum == 0:
    print(-1)
else:
    print(N-sum)

Submission status: Accepted

Solution code:
N = int(input())
a = list(map(int,input().split()))
cur=1
res=0

for i in range(N):
    if(a[i]!=cur):
        res+=1
    else:
        cur+=1
if(cur==1): print(-1)
else: print(res)

Submission status: Accepted

Solution code:
n = int(input())
a = [int(i) for i in input().split()]

cnt = 0
pointer = 1
for i in range(n):
  if a[i] == pointer:
    pointer += 1
  else:
    cnt += 1

if pointer == 1:
  print(-1)
else:
  print(cnt)

Submission status: Accepted

Solution code:
N = int(input())
a = list(map(int,input().split()))
k = 0
i = 1
flag = False
while k < N:
  if a[k] == i:
    i += 1
    k += 1
    flag = True
  else:
    k += 1
if flag == True:
  print(N-i+1)
else:
  print(-1)

Submission status: Accepted

Solution code:
a = int(input())
n = input().split()
b = 0
c = 0
flag = 0
for i in n:
    if not int(i) == b+1:
        c +=1
    else:
        b += 1
        flag = 1
if flag == 0:
    c = -1
print(c)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))
i=1
t=0
for x in a:
  if x!=i:
    t+=1
  else:
    i+=1
if len(a)==t:
  t=-1
print(t)

Submission status: Accepted

Solution code:
n=int(input())
L = list(map(int, input().split()))

d=0
c=1
for i in range(len(L)):
    if L[i]==c:
        c+=1
    else:
        d+=1

if n==d:
    d=-1
print(d)

Submission status: Accepted

Solution code:
N=int(input())
b=list(map(int,input().split()))
var=1
_break=0
for i in range(N):
  if b[i] != var:
    _break+=1
    
  else:
    var+=1
  
if _break==N:
  print(-1)
else:
  print(_break)

Submission status: Accepted

Solution code:
# -*- coding: utf-8 -*-
N = int(input())
a = [int(i) for i in input().split()]

ans = 0
tmp = 1
for i in range(N):
    if a[i] == tmp:
        tmp += 1
    else:
        ans += 1

if ans == N:
    ans = -1

print(ans)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int, input().split()))

x = 0
for ai in a:
    if ai == x + 1:
        x += 1

ans = -1 if x == 0 else n - x
print(ans)

Submission status: Accepted

Solution code:
n=int(input())
A=[int(i) for i in input().split()]

k=1
cnt=0
for i in range(n):
  if A[i]!=k:
    cnt+=1
  else:
    k+=1
if cnt==n:
  print(-1)
else:
  print(cnt)

Submission status: Accepted

Solution code:
A = int(input())
B = list(map(int, input().split())) 

N = 0
C = 1

for num in B:
  if num == C:
    C += 1
    N += 1

ANSWER = 0

if N == 0:
  ANSWER = -1
else:
  ANSWER = A - N
  
print(ANSWER)

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int,input().split()))
 
num = 1
ans = 0
 
for i in range(n):
  if num == a[i]:
    num += 1
 
if num == 1:
  ans = -1
else:
  ans = n - num + 1
 
print(ans)

Submission status: Accepted

Solution code:
N = int(input())
A = list(map(int, input().split()))
now = 1
for a in A:
    if a == now:
        now += 1
if now != 1:
    print(N-now+1)
else:
    print('-1')

Submission status: Accepted

Solution code:
n = int(input())
a = list(map(int,input().split()))
left = 0
num = 1
start = 0
while True:
    Flag = True
    for i in range(start,n):
        if a[i] == num:
            left += 1
            start = i
            Flag = False
            num += 1
            break
    if Flag:
        break
if left == 0:
    ans = -1
else:
    ans = n - left
print(ans)

Submission status: Accepted

Solution code:
# D - Brick Break
N = int(input())
Alist = list(map(int, input().split()))
if min(Alist) != 1:
    print(-1)
else:
    max_num = 1
    i = 0
    while i < N:
        a = Alist[i]
        if a == max_num:
            max_num += 1
        i += 1
    print(N - max_num + 1)

Submission status: Accepted

Solution code:
N=int(input())
numlist=[int(i) for i in input().split()]


n=1

for i in range(N):
    if numlist[i]==n:
        n+=1
if n==1:
    print(-1)
else:
    print(N-n+1)

Submission status: Accepted

Solution code:
N = int(input())
A = list(map(int, input().split()))

focus = 1
for i in range(N):
    if A[i] == focus:
        focus += 1

print(N-focus+1 if focus > 1 else -1)

Submission status: Accepted

Solution code:
N = int(input())
a = list(map(int, input().split()))
count = 0
next_number = 1

for i in range(0,N):
  if a[i]==next_number:
    next_number += 1
  else:
    count += 1
if count == N:
  count = -1
print(count)