为什么样例1能过，样例2却不行

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

int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};
int n, m, start_x, start_y, end_x, end_y, q[10010][3]={0}, h = 1, t = 1, b[200][200] = {0};
char a[200][200]={0};
int main() {
	// ...（变量声明和输入部分）


	cin >> n >> m >> start_x >> start_y >> end_x >> end_y;
	start_x++;
	start_y++;
//	end_x;
//	end_y;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			cin >> a[i][j];
		}
	}
	memset(b,0,sizeof(b));
	// 初始化队列，设置入口坐标
	q[1][0] = start_x;
	q[1][1] = start_y;
	q[1][2] = 0; // 起点的步数为0
	b[start_x][start_y] = 1; // 标记起点已访问

	// 开始广度优先搜索
	while (h <= t) {
		// 打印当前队列头部的坐标
		cout << "处理队列头部: (" << q[h][0] << ", " << q[h][1] << ")" << endl;

		// 遍历四个可能的移动方向
		for (int i = 0; i < 4; i++) {
			int nr = q[h][0] + dx[i], nc = q[h][1] + dy[i];

			// 打印尝试扩展的坐标
			cout << "尝试扩展到: (" << nr << ", " << nc << ")" << endl;

			// 检查新位置是否在地图内、是否可走以及是否未访问过
			if (nr >= 0 && nr <= n && nc >= 0 && nc <= m && a[nr][nc] == '.' && b[nr][nc] == 0) {
				t++;
				q[t][0] = nr;
				q[t][1] = nc;
				q[t][2] = q[h][2] + 1;
				b[nr][nc] = 1; // 更新步数
				// 打印添加到队列的坐标和步数
				cout << "添加到队列: (" << nr << ", " << nc << ") 步数: " << q[t][2] << endl;
			} else {
				// 打印不可扩展的坐标
				cout << "无法扩展到: (" << nr << ", " << nc << ")" << endl;
			}
			if (nr == end_x && nc == end_y) {
				cout << "总共步数:" << q[t][2]+1 << endl;
				return 0;
			}
		}
		h++;
	}

	// 如果没有找到路径，打印队列的状态
	cout << "队列耗尽，未找到路径。" << endl;
	for (int i = 1; i <= t; i++) {
		cout << "队列元素 " << i << ": (" << q[i][0] << ", " << q[i][1] << ", " << q[i][2] << ")" << endl;
	}

	cout << -1 << endl;
	return 0;
}
//样例1：
//10 10
//1 1
//9 10
//##########
//#..#######
//##..######
//###..#####
//####.#####
//####.#####
//####..####
//#####...##
//#######...
//##########
//样例2：
//15 15
//1 1
//14 15
//################
//#.##############
//#..#############
//##...###########
//##.#.###########
//##.#..##########
//##..#..#########
//###.##.#########
//###.##...#######
//###.##.#.#######
//###.##.#..######
//###..#..#..#####
//####.##.##.#####
//####............
//################

是哪里的问题呢？（不喜勿喷）