#include <iostream>
#include <queue>
using namespace std;
struct coord {
    int x, y, t;
};
const int maxn = 305;
bool flag[maxn][maxn], f[105];
char c[maxn][maxn];
coord p[3][105], start;
int n, m;
queue<coord> q;
int jx[5] = { 0,1,0,-1,0 };
int jy[5] = { 0,0,1,0,-1 };
int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            do { cin >> c[i][j]; } while (c[i][j] == '\n' || c[i][j] == '\r');
            if (c[i][j] >= 'A' && c[i][j] <= 'Z')
                if (p[1][c[i][j]].x == 0)
                    p[1][c[i][j]].x = i, p[1][c[i][j]].y = j;
                else
                    p[2][c[i][j]].x = i, p[2][c[i][j]].y = j;
            if (c[i][j] == '@')
                start.x = i, start.y = j, start.t = 0;
        }
    }
    q.push(start);
    while (!q.empty()) {
        coord l = q.front();
        q.pop();
        int nx = l.x, ny = l.y, nt = l.t;
        if (c[nx][ny] == '=') {
            cout << nt;
            break;
        }
        if (flag[nx][ny] == false) {
            if (c[nx][ny] >= 'A' && c[nx][ny] <= 'Z') {
                if (f[c[nx][ny]] == false) {
                    if (p[1][c[nx][ny]].x == nx && p[1][c[nx][ny]].y == ny) {
                        coord r;
                        r.x = p[2][c[nx][ny]].x, r.y = p[2][c[nx][ny]].y, r.t = nt;
                        q.push(r);
                        f[c[nx][ny]] = true;
                        continue;
                    }
                    else {
                        coord r;
                        r.x = p[1][c[nx][ny]].x, r.y = p[1][c[nx][ny]].y, r.t = nt;
                        q.push(r);
                        f[c[nx][ny]] = true;
                        continue;
                    }
                }
                else
                    f[c[nx][ny]] = false;
            }
            for (int i = 1; i <= 4; i++) {
                int mx = nx + jy[i], my = ny + jx[i];
                if (mx <= n && mx > 0 && my <= m && my > 0 && flag[mx][my] == false && c[mx][my] != '#') {
                    coord r;
                    r.x = mx, r.y = my, r.t = nt + 1;
                    q.push(r);
                    if (!(c[nx][ny] >= 'A' && c[nx][ny] <= 'Z'))
                        flag[nx][ny] = true;
                }
            }
        }
    }
    return 0;
}

其中有一个数据点，是：

19 24
########################
#@..A.#BR#RF#E...#.....#
#...#.##.##.####.#.###.#
#####BA#.##.#Q.#.#.#...#
#D...C#W.#FQ####...#.#.#
####C########D.E####.#.#
#...#...#....#W#...#.#.#
#.#.#.#.#.#...#..#.#.#.#
#.#...#...#..T#..#...#.#
#N##############.#####.#
#X#X#M#J#V###V.#.......#
#Z#Y#Y#M#J#########.####
#..#.#.#.##......#.....#
#.#...N#....#...#......#
#.#.####.####..#.......#
#.#......#....#........#
#.########.###.......###
#....................#T=
########################

请问这个数据点中奶牛如何到达出口？