#include <iostream>

#include <cmath>

#include <list>

#include <vector>

using namespace std;

char board[50][50];

bool visited[50][50];

int N, M;

int ans = 2500;

vector<pair<int, int>> v;

bool include[11];

list<pair<pair<int, int>, int>> bfsQueue;

bool checkVirusSpread()

{

int i, j;

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

{

if (board[i][j] == '0' && !visited[i][j])

return false;

}

}

return true;

}

void resetVisited()

{

int i, j;

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

{

visited[i][j] = false;

}

}

}

int dx[4] = {0, 0, 1, -1};

int dy[4] = {1, -1, 0, 0};

int brute(int n, int selected)

{

if (selected == M)

{

resetVisited();

bfsQueue.clear();

for (int i = 0; i < 11; i++)

{

if (include[i])

{

bfsQueue.push_front({{v[i].first, v[i].second}, 0});

}

}

int time = 0;

while (!bfsQueue.empty())

{

int x = bfsQueue.front().first.first;

int y = bfsQueue.front().first.second;

int t = bfsQueue.front().second;

bfsQueue.pop_front();

for (int i = 0; i < 4; i++)

{

int tx = x + dx[i];

int ty = y + dy[i];

if (tx >= 0 && ty >= 0 && tx < N && ty < N && board[tx][ty] != '1' && !visited[tx][ty])

{

if (board[tx][ty] == '0')

time = max(time, t + 1);

bfsQueue.push_back({{tx, ty}, t + 1});

visited[tx][ty] = true;

}

}

}

if (checkVirusSpread())

return time;

else

return 5000;

}

if (n + 1 >= v.size())

return 5000;

int res = 5000;

include[n + 1] = true;

res = min(res, brute(n + 1, selected + 1));

include[n + 1] = false;

res = min(res, brute(n + 1, selected));

return res;

}

int main()

{

ios::sync_with_stdio(0);

cin.tie(0);

int i, j;

cin >> N >> M;

for (i = 0; i < N; i++)

{

for (j = 0; j < N; j++)

{

cin >> board[i][j];

if (board[i][j] == '2')

v.push_back({i, j});

}

}

int ans = 5000;

include[0] = true;

ans = min(ans, brute(0, 1));

include[0] = false;

ans = min(ans, brute(0, 0));

if (ans == 5000)

cout << "-1\n";

else

cout << ans << "\n";

return 0;

}