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
}

C++: #include<iostream>
#include<queue>
using namespace std;

typedef pair<int ,int > P;
typedef pair<int, P> P2;

bool v[30][30],vb[30][30][20];
string g[30],L;
int h,w,s;
int ay,ax,by,bx;

int main(){
  while(cin >> h >> w , h||w){
    for(int i=0;i<h;i++)cin >> g[i];
    cin >> L;
    s = L.size();
    for(int i=0;i<h;i++)
      for(int j=0;j<w;j++){
	if(g[i][j] == 'A'){
	  g[i][j] == '.';
	  ay = i; ax = j;
	}
	if(g[i][j] == 'B'){
	  g[i][j] == '.';
	  by = i; bx = j;
	}
	v[i][j] = false;
	for(int k=0;k<s;k++)vb[i][j][k] = false;
      }

    int t = 0;
    queue<P2> q;
    q.push(P2(0,P(ay,ax)));

    while(!q.empty()){
      P2 p = q.front();q.pop();
      /*
      cout << "[" << p.first << " " << p.second.first << " " << p.second.second << "]" << endl;
      cout << by << " " << bx << endl;
      */
      if(p.first==t+1){
	vb[by][bx][t%s] = true;
	if(v[by][bx])break;
	if(L[t%s] == '8' && 0<by)by--;
	if(L[t%s] == '6' && bx<w-1)bx++;
	if(L[t%s] == '2' && by<h-1)by++;
	if(L[t%s] == '4' && 0<bx)bx--;
	t++;
      }

      v[p.second.first][p.second.second] = true;

      int dy[] = {-1,0,1,0}, dx[] = {0,1,0,-1};
      for(int i=0;i<4;i++){
	int sy = p.second.first + dy[i] , sx = p.second.second + dx[i];
	if(sy<0 || sx<0 || h<=sy || w<=sx)continue;
	if(v[sy][sx] || g[sy][sx]=='#')continue;
	q.push(P2(p.first+1,P(sy,sx)));
      }
    }

    if(v[by][bx])cout << t << " " << by << " " << bx << endl;
    else {
      for(int i=0;;i++){
	if(vb[by][bx][(t+i)%s]){
	  //cout << t+i << endl;
	  cout << "impossible\n";
	  break;
	}
	vb[by][bx][(t+i)%s] = true;
	if(L[(t+i)%s] == '2' && 0<by)by--;
	if(L[(t+i)%s] == '6' && bx<w-1)bx++;
	if(L[(t+i)%s] == '8' && by<h-1)by++;
	if(L[(t+i)%s] == '4' && 0<bx)bx--;
	if(v[by][bx]){
	  cout << t+i+1 << " " << by << " " << bx << endl;
	  break;
	}
      }
    }
  }
}

C++: #include<iostream>
#include<algorithm>
#include<climits>
#include<vector>
#include<queue>
#include<stack>
#include<cmath>
#include<string.h>

using namespace std;

int h,w,sx,sy,gx,gy;
int dx[4]={1,0,-1,0};
int dy[4]={0,-1,0,1};

char ma[21][21];
int co[21][21];
bool visited[21][21];

int main(){
    while(cin>>h>>w,h){
        for(int i=0;i<h;i++){
            for(int j=0;j<w;j++){
                co[i][j]=INT_MAX;
                cin>>ma[i][j];
                if(ma[i][j]=='A'){
                    sx=j,sy=i;
                } else if(ma[i][j]=='B'){
                    gx=j,gy=i;
                }
            }
        }
        memset(visited, 0, sizeof(visited));
        queue<pair<pair<int,int>,int> >q;
        q.push(make_pair(make_pair(sx, sy), 0));
        while(q.size()){
            pair<pair<int,int>,int> p = q.front();
            visited[p.first.second][p.first.first]=1;
            co[p.first.second][p.first.first]=p.second;
           // cout<<p.first.second<<"  "<<p.first.first<<"  "<<p.second<<endl;
            q.pop();
            for(int i=0;i<4;i++){
                int nx=p.first.first+dx[i];
                int ny=p.first.second+dy[i];
                if(nx>=0&&nx<w&&ny>=0&ny<h&&ma[ny][nx]!='#'&&co[ny][nx]==INT_MAX&&ma[ny][nx]!='A'&&!visited[ny][nx]){
                    q.push(make_pair(make_pair(nx, ny), p.second+1));
                }
            }
        }
        string pat;
        cin>>pat;
        int go=0;
        for(int j=0;;j++){
            int i=j%pat.length();
         //   cout<<gy<<" "<<gx<<" "<<co[gy][gx]<<" "<<INT_MAX<<endl;
            if(co[gy][gx]<=go){
                cout<<go<<" "<<gy<<" "<<gx<<endl;
                break;
            }
            if(go>INT_MAX/190){
                cout<<"impossible"<<endl;
                break;
            }
            if(pat[i]=='5'){
                
            } else if(pat[i]=='8'){
                gy--;
            } else if(pat[i]=='6'){
                gx++;
            } else if(pat[i]=='4'){
                gx--;
            } else if(pat[i]=='2'){
                gy++;
            }
            gy=max(0,gy);
            gy=min(h-1,gy);
            gx=max(0,gx);
            gx=min(w-1,gx);
            go++;
        }
    }
}