TOMATO

 

 

import java.util.Scanner; 
import java.util.ArrayList; 
import java.util.Queue; 
import java.util.LinkedList; 

public class Main{ 
    public static int[] dh = new int[]{1,-1}; 
    public static int[] dy = new int[]{1,0,-1,0}; 
    public static int[] dx = new int[]{0,1,0,-1}; 
    public static int height,sero,garo; 
    public static int[][][] map,score; 
    public static boolean[][][] v; 
    public static ArrayList arrList = new ArrayList();  
    public static void main(String[] args){ 

      Scanner scan = new Scanner(System.in); 
      input(scan); 
      if(!checkZero()){System.out.println(0);return;} 
      setArrList(); 
      // System.out.println(arrList.toString()); 
      bfs(); 
      // printS(); 
       
      answer(); 
      scan.close();       
    } 
     
    public static void printS() 
    { 
      for(int i=0;i<height;i++) 
      { 
        for(int j=0;j<sero;j++) 
        { 
          for(int k=0;k<garo;k++) 
          {System.out.print(score[i][j][k]+" ");}System.out.println(); 
        } 
      } 
    } 
     
    public static void answer() 
    { 
      int max=-1; 
      for(int i=0;i<height;i++) 
      { 
        for(int j=0;j<sero;j++) 
        { 
          for(int k=0;k<garo;k++) 
          { 
            if(score[i][j][k]>max) 
            { 
              max=score[i][j][k]; 
              
            }  
            if(score[i][j][k]==0){System.out.println(-1);return;} 
          } 
        } 
      } 
      System.out.println(max); 
    } 
     
    public static void input(Scanner scan) 
    { 
      garo = scan.nextInt();sero = scan.nextInt();height=scan.nextInt(); 
      map = new int[height][sero][garo]; score= new int[height][sero][garo]; v = new boolean[height][sero][garo];  
      for(int i=0;i<height;i++) 
      { 
        for(int j=0;j<sero;j++) 
        { 
          for(int k=0;k<garo;k++) 
          { 
            map[i][j][k] = scan.nextInt(); 
          } 
        } 
      } 
    } 
     
    public static void setArrList() 
    { 
      for(int i=0;i<height;i++) 
      { 
        for(int j=0;j<sero;j++) 
        { 
          for(int k=0;k<garo;k++) 
          { 
            if(map[i][j][k]==1)arrList.add(new Point(i,j,k,0)); 
          } 
        } 
      } 
      
    } 
     
    public static void bfs() 
    { 
      Queue q = new LinkedList(); 
      for(int i=0;i<arrList.size();i++) 
      { 
        q.add(arrList.get(i)); 
        int h1 = arrList.get(i).h; 
        int x1 = arrList.get(i).x; 
        int y1 = arrList.get(i).y; 
        v[h1][x1][y1]=true; 
      } 
       
      while(!q.isEmpty()) 
      { 
        Point pt = q.peek(); 
        q.remove(); 
         
        int ch = pt.h; 
        int cx = pt.x; 
        int cy = pt.y; 
        int cVal = pt.cVal; 
         
        if(cVal==0){score[ch][cx][cy]=-1;} 
         
        for(int i=0;i<4;i++) 
        { 
          int nx = cx+dx[i]; 
          int ny = cy+dy[i]; 
          if(nx>=0 && nx=0 && ny<garo) 
          { 
            if(v[ch][nx][ny]==false && map[ch][nx][ny]==0) 
            { 
              map[ch][nx][ny]=1;v[ch][nx][ny]=true; 
              score[ch][nx][ny]=cVal+1; 
              q.add(new Point(ch,nx,ny,cVal+1)); 
            } 
          } 
           
        } 
         
        for(int i=0;i<2;i++) 
        { 
          int nh = ch+dh[i]; 
          if(nh>=0 && nh<height) 
          { 
            if(v[nh][cx][cy]==false && map[nh][cx][cy]==0) 
            { 
              map[nh][cx][cy]=1;v[nh][cx][cy]=true; 
              score[nh][cx][cy]=cVal+1; 
              q.add(new Point(nh,cx,cy,cVal+1)); 
            } 
          } 
        } 
         
      } 
       
       
    } 
     
    public static boolean checkZero() 
    { 
      for(int i=0;i<height;i++) 
      { 
        for(int j=0;j<sero;j++) 
        { 
          for(int k=0;k<garo;k++) 
          { 
            if(map[i][j][k]==0)return true; 
          } 
        } 
      } 
      return false; 
    } 
} 

class Point 
{ 
   
  int h; 
  int x; 
  int y; 
  int cVal; 
  public Point(int h,int x,int y,int cVal) 
  { 
    this.h = h;this.x=x;this.y=y;this.cVal = cVal; 
  } 
  @Override 
  public String toString() 
  { 
    return "[ h:"+h+" x:"+x+" y:"+y+" cVal:"+cVal+"]"; 
  } 
}