1681D - Required Length - CodeForces Solution

import sys
from bisect import bisect_right, bisect_left
import os
import sys
from io import BytesIO, IOBase
from math import factorial, floor, sqrt, inf, ceil, gcd
from collections import defaultdict, deque, Counter
from functools import cmp_to_key

BUFSIZE = 8192
 
class FastIO(IOBase):
    newlines = 0
 
    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None
 
    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()
 
    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()
 
    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)
 
 
class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")
 
 
sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(s[:len(s) - 1])
def invr():
    return(map(int,input().split()))
def insr2():
    s = input()
    return(s.split(" "))



def build_mod_inverses(n, r, p):
    fact = [1] * (n + 1)
    for i in range(1, n + 1):
        fact[i] = i * fact[i - 1] % p
    
    inv = [1] * (n + 1)
    inv[n] = pow(fact[n], p - 2, p)
    for i in range(n - 1, -1, -1):
        inv[i] = (i + 1) * inv[i + 1] % p
    
    return fact, inv

def comb(n, r, p, fact, inv):
    return fact[n] * inv[r] % p * inv[n - r] % p if n >= r >= 0 else 0
 
def make_divisors(n):
    divisors = []
    for i in range(1, int(n**0.5)+1):
        if n % i == 0:
            divisors.append(i)
            if i != n // i and i != 1:
                divisors.append(n // i)
    return divisors

def dfs(graph, vertex):
    visited = set()
    tree = []
    deq = deque([vertex])
    while deq:
        vertex = deq.pop()
        if vertex not in visited:
            visited.add(vertex)
            deq.extend(graph[vertex])
            tree.append(vertex)
    return tree

def find_in_sorted_list(elem, sorted_list):
        'Locate the leftmost value exactly equal to x'
    i = bisect_left(sorted_list, elem)
    if i != len(sorted_list) and sorted_list[i] == elem:
        return i
    return -1


class SegmentTree:
    def __init__(self, data, default=0, func=lambda a, b: a+b):
        
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
 
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])
 
    def __delitem__(self, idx):
        self[idx] = self._default
 
    def __getitem__(self, idx):
        return self.data[idx + self._size]
 
    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1
 
    def __len__(self):
        return self._len
 
    def query(self, start, stop):
        if start == stop:
            return self.__getitem__(start)
        start += self._size
        stop += self._size
 
        res = self._default
        while start < stop:
            if start & 1:
                res = self._func(res, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res = self._func(res, self.data[stop])
            start >>= 1
            stop >>= 1
        return res
 
    def __repr__(self):
        return "SegmentTree({0})".format(self.data)



n, x = inlt()
depth = 0
start = (x, depth)
visited = set()

if set(str(x)) == set('1') or set(str(x)) == set('0') or set(str(x)) == set(['1', '0']):
    print(-1)
    sys.exit()

deq = deque([start])
while deq:
    vertex = deq.popleft()
    if vertex not in visited:
        visited.add(vertex)
        if len(str(vertex[0])) >= n:
            print(vertex[1])
            sys.exit()
        
        for num in str(vertex[0]):
            val = vertex[0] * int(num)
            depth = vertex[1]+1
            deq.append((val, depth))