RE

#include<bits/stdc++.h>
using namespace std;

struct Node{
	int r, c;
	Node(int _r, int _c){
		r = _r, c = _c;
	}
};

int max_n = 0;
bool v[1020][100];
int dirr[4] = {0, 0, -1, 1};
int dirc[4] = {-1, 1, 0, 0};
int w, h;

void bfs(vector<vector<char> > G, int r, int c){
	int num = 1;
	char cur = G[r][c];
	queue<Node> q;
	v[r][c]= 1;
	q.push(Node(r, c));
	while(!q.empty()){
		int len = q.size();
		for(int i = 0;i < len;i++){
			for(int j = 0;j < 4;j++){
				r = q.front().r + dirr[j]; c = q.front().c + dirc[j];
				if(r < h && c < w){
					if(!v[r][c] && G[r][c] == cur){
						num++;
						q.push(Node(r, c));
//						cout<<r<<" "<<c<<" "<<num<<endl;
						v[r][c] = 1;
					}
				}
			}
			q.pop();
		}
	}
	max_n = max(num, max_n);
}

int main(){
	char x;
	cin>>w>>h;
	memset(v, 0, sizeof(v));
	vector<vector<char> > G(h + 1);
	for(int i = 0;i < h;i++){
		for(int j = 0;j < w;j++){
			cin>>x;
			G[i].push_back(x);
		}
	}
	
	for(int i = 0;i < h;i++){
		for(int j = 0;j < w;j++){
			if(!v[i][j] && G[i][j] == '*') bfs(G, i, j);
		}
	}
	
	cout<<max_n;
	return 0;
}