#include<stdio.h>
#include<string.h>
#include<stdlib.h>
using namespace std;
#include<iostream>
#include<math.h>
#include<algorithm>
int n, m;
char board[1001][1001];
bool come[1001][1001];
long long maax = 0;
void dfs(int y, int x, long long sum)
{
	if (y > n || x > n || y < 1 || x < 1 || come[y][x])
	{
		return;
	}
	come[y][x] = 1;
	char mid = board[y][x];
	int turn = 0;
	if (board[y][x + 1] != mid)
		dfs(y, x + 1, sum + 1);
	else
		turn++;
	if (board[y][x - 1] != mid)
		dfs(y, x - 1, sum + 1);
	else
		turn++;
	if (board[y + 1][x] != mid)
		dfs(y + 1, x, sum + 1);
	else
		turn++;
	if (board[y - 1][x] != mid)
		dfs(y - 1, x, sum + 1);
	else
		turn++;
	maax = max(maax, sum);
	return;

}
int main()
{
	scanf("%d %d", &n, &m);
	getchar();
	for (int i = 1; i <= n; i++)
	{
		for (int t = 1; t <= n; t++)
			scanf("%c", &board[i][t]);
		getchar();
	}
	while (m-- > 0)
	{
		int y, x;
		scanf("%d%d", &y, &x);
		memset(come, 0, sizeof(come));
		dfs(y, x, 1);
		printf("%lld\n", maax);
		maax = 0;
	}
	return 0;
}

明明自己的数据和样例都过了，是我理解错题意了吗