#include <bits/stdc++.h>>
 
using namespace std;
 
#define For(i,a,b) for(int i=(int)(a);i<=(int)(b);++i)
#define Fill(a,b) memset(&a,b,sizeof(a))
 
const int dr[]={0,0,1,-1};
const int dc[]={1,-1,0,0};
 
int cols, rows, maxd, maxr, maxc;
char s[1005][1005], v[1005][1005];
 
void dfs(int r, int c, int l){
	if (l > maxd) {maxd=l; maxr=r; maxc=c;}
	v[r][c]=1;
	For(i,0,3) if (r+dr[i]>=0&&r+dr[i]<rows&&c+dc[i]>=0&&c+dc[i]<cols&&
			v[r+dr[i]][c+dc[i]]==0&&s[r+dr[i]][c+dc[i]]=='.')
		dfs(r+dr[i],c+dc[i],l+1);
}
 
int main(){	
	int t;
	scanf("%d",&t);
 
	For(z,1,t) {
		scanf("%d%d\n",&cols,&rows);
		For(j,1,rows) gets(s[j-1]);
		For(i,0,rows-1) For(j,0,cols-1) if (s[i][j]=='.') {
			maxd=-1; Fill(v,0);
			dfs(i,j,0);
 
			maxd=-1; Fill(v,0);
			dfs(maxr,maxc,0);
 
			printf("Maximum rope length is %d.\n",maxd);
			goto fin;
		}
		fin:;
	}
 
	return 0;
}

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