Go: package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
	"strconv"
)

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	dy := [4]int{-1, 0, 0, 1}
	dx := [4]int{0, -1, 1, 0}
	for {
		h := getNextInt(scanner)
		w := getNextInt(scanner)
		if h == 0 {
			break
		}
		grid := makeGrid(h, w)
		a := [2]int{}
		b := [2]int{}
		for i := 0; i < h; i++ {
			s := getNextString(scanner)
			for j := 0; j < w; j++ {
				if s[j] == '#' {
					grid[i][j] = math.MaxInt32
					continue
				}
				if s[j] == 'A' {
					a[0] = i
					a[1] = j
					continue
				}
				if s[j] == 'B' {
					b[0] = i
					b[1] = j
				}
				grid[i][j] = math.MaxInt32 - 1
			}
		}
		q := make([][2]int, 0)
		q = append(q, a)
		for len(q) > 0 {
			p := q[0]
			q = q[1:]
			for i := 0; i < 4; i++ {
				yy := p[0] + dy[i]
				xx := p[1] + dx[i]
				if yy == a[0] && xx == a[1] {
					continue
				}
				if yy < 0 || yy >= h {
					continue
				}
				if xx < 0 || xx >= w {
					continue
				}
				if grid[yy][xx] == math.MaxInt32 {
					continue
				}
				if grid[yy][xx] <= grid[p[0]][p[1]]+1 {
					continue
				}
				grid[yy][xx] = grid[p[0]][p[1]] + 1
				q = append(q, [2]int{yy, xx})
			}
		}
		move := getNextString(scanner)
		i := 0
		m := len(move)
		for {
			if i > 400 {
				fmt.Fprintln(writer, "impossible")
				break
			}
			if grid[b[0]][b[1]] <= i {
				fmt.Fprintln(writer, fmt.Sprintf("%d %d %d", i, b[0], b[1]))
				break
			}
			switch move[i%m] {
			case '8':
				if b[0] > 0 {
					b[0]--
				}
			case '6':
				if b[1]+1 < w {
					b[1]++
				}
			case '4':
				if b[1] > 0 {
					b[1]--
				}
			case '2':
				if b[0]+1 < h {
					b[0]++
				}
			}
			i++
		}
	}
}
func makeGrid(h, w int) [][]int {
	index := make([][]int, h, h)
	data := make([]int, h*w, h*w)
	for i := 0; i < h; i++ {
		index[i] = data[i*w : (i+1)*w]
	}
	return index
}

Python: from collections import deque
while True:
  h, w = map(int, input().split())
  if h == 0:
    break
  mp = [list("X" + input() + "X") for _ in range(h)]
  mp.insert(0, ["X"] * (w + 2))
  mp.append(["X"] * (w + 2))
  
  for y in range(h + 2):
    for x in range(w + 2):
      if mp[y][x] == "A":
        ax, ay = x, y
        mp[y][x] = "."
      if mp[y][x] == "B":
        bx, by = x, y
        mp[y][x] = "."
  INF = 1000
  dist_mp = [[INF] * (w + 2) for _ in range(h + 2)]
  dist_mp[ay][ax] = 0
  que = deque()
  que.append((0, ax, ay))
  vec = ((1, 0), (0, -1), (-1, 0), (0, 1))
  while que:
    d, x, y = que.popleft()
    for dx, dy in vec:
      nx, ny = x + dx, y + dy
      if mp[ny][nx] == "." and dist_mp[ny][nx] == INF:
        que.append((d + 1, nx, ny))
        dist_mp[ny][nx] = d + 1
  
  limit = d
  pattern = input()
  length = len(pattern)
  t = 0
  dic = {}
  while True:
    if t >= dist_mp[by][bx]:
      print(t, by - 1, bx - 1)
      break
    if t > limit:
      if (t % length, bx, by) in dic:
        print("impossible")
        break
      else:
        dic[(t % length, bx, by)] = True
    c = pattern[t % length]
    if c == "5": pass
    elif c == "8" and mp[by - 1][bx] != "X": by -= 1
    elif c == "6" and mp[by][bx + 1] != "X": bx += 1
    elif c == "4" and mp[by][bx - 1] != "X": bx -= 1
    elif c == "2" and mp[by + 1][bx] != "X": by += 1
    t += 1
  else:
    print("impossible")

C++: //35
#include<iostream>
#include<algorithm>
#include<string>

using namespace std;

char g[20][20];
int h,w;
int t[20][20];

void ff(int x,int y,int ct){
  if(x<0||w<=x||y<0||h<=y||t[y][x]<ct||g[y][x]=='#')return;
  t[y][x]=ct;
  for(int i=0;i<4;i++){
    int d[]={0,1,0,-1,0};
    ff(x+d[i],y+d[i+1],ct+1);
  }
}

int main(){
  while(cin>>h>>w,h|w){
    int ax,ay,bx,by;
    for(int y=0;y<h;y++){
      for(int x=0;x<w;x++){
	cin>>g[y][x];
	if(g[y][x]=='A'){
	  ax=x;
	  ay=y;
	}else if(g[y][x]=='B'){
	  bx=x;
	  by=y;
	}
      }
    }
    fill(t[0],t[20],1<<30);
    ff(ax,ay,0);
    string p;
    cin>>p;
    int e;
    for(e=0;e<100;e++){
      if(t[by][bx]<=e)break;
      char o=p[e%p.size()];
      int ny=by+(o=='2')-(o=='8');
      int nx=bx+(o=='6')-(o=='4');
      if(0<=ny&&ny<h&&0<=nx&&nx<w){
	by=ny;
	bx=nx;
      }
    }
    if(e<10000){
      cout<<e<<' '<<by<<' '<<bx<<endl;
    }else{
      cout<<"impossible"<<endl;
    }
  }
  return 0;
}