package contest; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.util.Arrays; import java.util.InputMismatchException; public class Q795 { InputStream is; PrintWriter out; String INPUT = ""; void solve() { int n = ni(), m = ni(); char[][] map = nm(n,m); char[][] nmap = new char[n+2][m+2]; for(int i = 0;i < n+2;i++)Arrays.fill(nmap[i], '.'); for(int i = 0;i < n;i++){ for(int j = 0;j < m;j++){ nmap[i+1][j+1] = map[i][j]; } } map = nmap; n += 2; m += 2; DJSet ds = new DJSet(n*m); for(int i = 0;i < n;i++){ for(int j = 0;j < m-1;j++){ if(map[i][j] == '.' && map[i][j+1] == '.'){ ds.union(i*m+j, i*m+j+1); } } } for(int i = 0;i < n-1;i++){ for(int j = 0;j < m;j++){ if(map[i][j] == '.' && map[i+1][j] == '.'){ ds.union(i*m+j, (i+1)*m+j); } } } for(int i = 0;i < n;i++){ for(int j = 0;j < m;j++){ for(int k = i-1;k <= i+1;k++){ for(int l = j-1;l <= j+1;l++){ if(k >= 0 && k < n && l >= 0 && l < m && map[i][j] == 'x' && map[k][l] == 'x'){ ds.union(i*m+j, k*m+l); } } } } } int z = ds.count(); boolean[][] g = new boolean[z][z]; int[] ind = new int[n*m]; int[] iind = new int[n*m]; int[] size = new int[n*m]; Arrays.fill(ind, -1); int p = 0; for(int i = 0;i < n*m;i++){ if(ds.upper[i] < 0){ ind[i] = p; iind[p] = i; size[p] = -ds.upper[i]; p++; } } int[] dr = { 1, 0, -1, 0 }; int[] dc = { 0, 1, 0, -1 }; for(int i = 0;i < n;i++){ for(int j = 0;j < m;j++){ if(map[i][j] == '.'){ for(int k = 0;k < 4;k++){ int nr = i + dr[k], nc = j + dc[k]; if(nr >= 0 && nr < n && nc >= 0 && nc < m && map[nr][nc] == 'x'){ g[ind[ds.root(i*m+j)]][ind[ds.root(nr*m+nc)]] = true; g[ind[ds.root(nr*m+nc)]][ind[ds.root(i*m+j)]] = true; } } } } } int root = ind[ds.root(0)]; // tf(g); int[] res = dfs(root, -1, g, iind, size); out.println(Math.max(res[0], res[1])); } public static void tf(boolean[][] b) { for (boolean[] r : b) { char[] s = new char[r.length]; for (int i = 0; i < r.length; i++) s[i] = r[i] ? '#' : '.'; System.out.println(new String(s)); } System.out.println(); } static int[] dfs(int cur, int pre, boolean[][] g, int[] iind, int[] size) { int n = g.length; int r1 = 0; int r0 = 0; for(int i = 0;i < n;i++){ if(g[cur][i] && i != pre){ int v = 0, w = 0; int ap = 0; for(int j = 0;j < n;j++){ if(g[i][j] && j != cur){ int[] res = dfs(j, i, g, iind, size); v = Math.max(v, res[1]); v = Math.max(v, res[0] + size[i]); w = Math.max(w, res[1]); w = Math.max(w, res[0]); if(++ap > 1)throw new RuntimeException(); } } r1 += v; r0 += w; if(ap == 0){ r1 += size[i]; } } } return new int[]{r0, r1}; } public static class DJSet { public int[] upper; public DJSet(int n) { upper = new int[n]; Arrays.fill(upper, -1); } public int root(int x) { return upper[x] < 0 ? x : (upper[x] = root(upper[x])); } public boolean equiv(int x, int y) { return root(x) == root(y); } public boolean union(int x, int y) { x = root(x); y = root(y); if (x != y) { if (upper[y] < upper[x]) { int d = x; x = y; y = d; } upper[x] += upper[y]; upper[y] = x; } return x == y; } public int count() { int ct = 0; for (int u : upper) if (u < 0) ct++; return ct; } } void run() throws Exception { is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes()); out = new PrintWriter(System.out); long s = System.currentTimeMillis(); solve(); out.flush(); if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms"); } public static void main(String[] args) throws Exception { new Q795().run(); } private byte[] inbuf = new byte[1024]; private int lenbuf = 0, ptrbuf = 0; private int readByte() { if(lenbuf == -1)throw new InputMismatchException(); if(ptrbuf >= lenbuf){ ptrbuf = 0; try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf <= 0)return -1; } return inbuf[ptrbuf++]; } private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); } private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; } private double nd() { return Double.parseDouble(ns()); } private char nc() { return (char)skip(); } private String ns() { int b = skip(); StringBuilder sb = new StringBuilder(); while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ') sb.appendCodePoint(b); b = readByte(); } return sb.toString(); } private char[] ns(int n) { char[] buf = new char[n]; int b = skip(), p = 0; while(p < n && !(isSpaceChar(b))){ buf[p++] = (char)b; b = readByte(); } return n == p ? buf : Arrays.copyOf(buf, p); } private char[][] nm(int n, int m) { char[][] map = new char[n][]; for(int i = 0;i < n;i++)map[i] = ns(m); return map; } private int[] na(int n) { int[] a = new int[n]; for(int i = 0;i < n;i++)a[i] = ni(); return a; } private int ni() { int num = 0, b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private long nl() { long num = 0; int b; boolean minus = false; while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-')); if(b == '-'){ minus = true; b = readByte(); } while(true){ if(b >= '0' && b <= '9'){ num = num * 10 + (b - '0'); }else{ return minus ? -num : num; } b = readByte(); } } private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); } }