import java.io.InputStream; import java.io.InputStreamReader; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayDeque; import java.util.ArrayList; import java.util.Arrays; import java.util.Comparator; import java.util.Deque; import java.util.HashMap; import java.util.InputMismatchException; import java.util.Map; import java.util.PriorityQueue; import java.math.BigInteger; public class Main{ static final InputStream in=System.in; static final PrintWriter out=new PrintWriter(System.out); static final int INF=Integer.MAX_VALUE/2; static final long LINF=Long.MAX_VALUE/2; static final int[] dx={1,0,-1,0}; static final int[] dy={0,1,0,-1}; public static void main(String[] args) throws IOException{ InputReader ir=new InputReader(in); int w=ir.nextInt(); int h=ir.nextInt(); int ans=INF; char[][] map=new char[h][w]; boolean[][] isCave1=new boolean[h][w]; int[][] dist=new int[h][w]; for(int i=0;i=0&&nx=0&&ny=0&&nx=0&&ny que=new ArrayDeque(); dist[sx][sy]=0; que.offerLast(new Pair(sx,sy)); while(!que.isEmpty()){ Pair p=que.pollFirst(); int x=p.x; int y=p.y; for(int i=0;i<4;i++){ int nx=x+dx[i]; int ny=y+dy[i]; if(nx>=0&&nx=0&&nydist[x][y]){ que.offerLast(new Pair(nx,ny)); dist[nx][ny]=dist[x][y]+1; } } } } return INF; } static class Pair{ public static int x; public static int y; public Pair(int x,int y){ this.x=x; this.y=y; } public static final Comparator DISTANCE_ORDER=new Comp(); private static class Comp implements Comparator{ public int compare(Pair p1,Pair p2){ return p1.x>p2.x?1:p1.x=lenbuf){ curbuf= 0; try{ lenbuf=in.read(buffer); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf<=0) return -1; } return buffer[curbuf++]; } public boolean isSpaceChar(int c){return !(c>=33&&c<=126);} private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;} public String next() { int b=skip(); StringBuilder sb=new StringBuilder(); while(!isSpaceChar(b)){ sb.appendCodePoint(b); b=readByte(); } return sb.toString(); } public int nextInt() { int c=readByte(); while (isSpaceChar(c)) c=readByte(); boolean minus=false; if (c=='-') { minus=true; c=readByte(); } int res=0; do{ if(c<'0'||c>'9') throw new InputMismatchException(); res=res*10+c-'0'; c=readByte(); }while(!isSpaceChar(c)); return (minus)?-res:res; } public long nextLong() { int c=readByte(); while (isSpaceChar(c)) c=readByte(); boolean minus=false; if (c=='-') { minus=true; c=readByte(); } long res = 0; do{ if(c<'0'||c>'9') throw new InputMismatchException(); res=res*10+c-'0'; c=readByte(); }while(!isSpaceChar(c)); return (minus)?-res:res; } public int[] toIntArray(int n){ int[] a=new int[n]; for(int i=0;i