#include <cmath>#include <cstdio>#include <cstdlib>#include <map>#include <set>#include <list>#include <deque>#include <queue>#include <stack>#include <bitset>#include <vector>#include <string>#include <limits>#include <algorithm>#include <cstring> #include <functional>using namespace std;const int dir[4][2] = { {1, 0}, {0, -1}, {-1, 0}, {0, 1}};struct Status{ char x, y, z;};inline int c2i(char c){ switch(c) { case 'b': return 1; case 'y': return 2; case 'r': return 4; case 'g': return 8; } return 0;}inline int C2i(char C){ switch(C) { case 'B': return 1; case 'Y': return 2; case 'R': return 4; case 'G': return 8; } return 0;}char mp[102][102];int mind[102][102][16];Status q[100 * 100 * 16];int p, t;int main(void){ static int r, c, ans; static int x, y, z, xx, yy, zz; memset(mp[0], '#', sizeof(mp[0])); while(scanf("%d%d", &r, &c) != EOF && r + c > 0) { p = t = 0; for (int i = 1; i <= r; i++) { mp[i][0] = '#'; scanf("%s", mp[i] + 1); for (int j = 1; j <= c; j++) { for (int k = 0; k < 16; k++) mind[i][j][k] = -1; if(mp[i][j] == '*') { q[t].x = i; q[t].y = j; q[t].z = 0; mind[i][j][0] = 0; ++t; mp[i][j] = '.'; } } mp[i][c + 1] = '#'; } memset(mp[r + 1], '#', (c + 1) * sizeof(char)); ans = -1; while(p < t) { x = q[p].x; y = q[p].y; z = q[p].z; for (int d = 0; d < 4; d++) { xx = x + dir[d][0]; yy = y + dir[d][1]; if(mp[xx][yy] == '#') continue; else if(mp[xx][yy] == 'X') { ans = mind[x][y][z] + 1; p = t; break; } else if(mp[xx][yy] == '.') { zz = z; if(mind[xx][yy][zz] != -1) continue; } else if(islower(mp[xx][yy])) { zz = (z | c2i(mp[xx][yy])); if(mind[xx][yy][zz] != -1) continue; } else if(isupper(mp[xx][yy])) { zz = z; if((zz & C2i(mp[xx][yy])) == 0 || mind[xx][yy][zz] != -1) continue; } else continue; q[t].x = xx; q[t].y = yy; q[t].z = zz; mind[xx][yy][zz] = mind[x][y][z] + 1; ++t; } ++p; } if(ans == -1) puts("The poor student is trapped!"); else printf("Escape possible in %d steps.n", ans); } return 0;}
