Go: package main

import (
	"bufio"
	"container/list"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		w, h := io.NextInt(), io.NextInt()
		if w == 0 {
			break
		}
		xWall := make([][]int, h)
		yWall := make([][]int, h)
		for i := 0; i < h; i++ {
			xWall[i], yWall[i] = make([]int, w), make([]int, w)
			for j := 0; j < w; j++ {
				xWall[i][j], yWall[i][j] = -1, -1
			}
		}
		for i := 0; i < h*2-1; i++ {
			if i%2 == 0 {
				for j := 0; j < w-1; j++ {
					xWall[i/2][j] = io.NextInt()
				}
			} else {
				for j := 0; j < w; j++ {
					yWall[i/2][j] = io.NextInt()
				}
			}
		}
		//io.Println(bfs(w, h, xWall, yWall))
		fmt.Println(bfs(w, h, xWall, yWall))
	}
}

type P struct {
	x, y int
}

func bfs(w, h int, x, y [][]int) int {
	d := make([][]int, h)
	for i := 0; i < h; i++ {
		d[i] = make([]int, w)
	}
	q := list.New()
	q.PushBack(P{0, 0})
	d[0][0] = 1

	for q.Len() != 0 {
		pos := q.Remove(q.Front()).(P)
		if pos.x == w-1 && pos.y == h-1 {
			break
		}
		if pos.x > 0 && x[pos.y][pos.x-1] == 0 && d[pos.y][pos.x-1] == 0 {
			d[pos.y][pos.x-1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x - 1, pos.y})
		}
		if pos.x < w-1 && x[pos.y][pos.x] == 0 && d[pos.y][pos.x+1] == 0 {
			d[pos.y][pos.x+1] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x + 1, pos.y})
		}
		if pos.y > 0 && y[pos.y-1][pos.x] == 0 && d[pos.y-1][pos.x] == 0 {
			d[pos.y-1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y - 1})
		}
		if pos.y < h-1 && y[pos.y][pos.x] == 0 && d[pos.y+1][pos.x] == 0 {
			d[pos.y+1][pos.x] = d[pos.y][pos.x] + 1
			q.PushBack(P{pos.x, pos.y + 1})
		}
	}
	return d[h-1][w-1]
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

struct box {
	int cost;
	bool flag;
};

#define dprintf(arg1, ... ) printf( arg1, __VA_ARGS__)
//#define dprintf(arg1, ... ) 


char* replnext( char** ppos ) {
	char* oldpos = *ppos;
	*ppos = strchr( *ppos, ' ' );
	if ( *ppos == NULL ) { return oldpos; }
	**ppos = '\0';
	(*ppos)++;
	return oldpos;
}

int main(void) {
	
	while(1) {
		int width, height;
		scanf("%d %d\n", &width, &height);
		if ( width == 0 && height == 0 ) { break; }
		
		struct box map[30/*h*/][30/*w*/];
		unsigned char tatekabe[30][31];
		unsigned char yokokabe[31][30];
		
		char buf[256];
		
		for ( int loo=0; loo< (height*2 - 1); loo++ ) {
			int i = loo/2;
			
			fgets(buf, 256, stdin);
			*(strchr(buf, '\n')) = '\0';
			char* pos = buf;
			
			if ( loo % 2 == 0 ) {
				//tatekabe
				tatekabe[i][0] = 1;
				tatekabe[i][width] = 1;
				
				if ( buf[0] == ' ') { replnext(&pos); }
				for ( int loo2 = 1; loo2 < width; loo2++ ) {
					tatekabe[i][loo2] = atoi( replnext(&pos) );
				}
			} else {
				//yokokabe
				for ( int loo2 = 0; loo2 < width; loo2++ ) {
					yokokabe[i+1][loo2] = atoi( replnext(&pos) );
				}
			}
		}
		
		for ( int loo=0; loo<width; loo++ ) {
			for ( int loo2 = 0; loo2<height; loo2++ ) {
				map[loo2][loo].cost = INT_MAX;
				map[loo2][loo].flag = false;
			}
			yokokabe[0][loo] = 1;
			yokokabe[height][loo] = 1;
		}
		//yokokabe[0][0] = 0;
		//yokokabe[height][width-1] = 0;
		
		map[0][0].cost = 0;

		while(1) {
			int min_x = -1, min_y = -1;
			int minval = INT_MAX;
			for ( int loo=0; loo<width; loo++ ) {
				for ( int loo2 = 0; loo2<height; loo2++ ) {
					if ( map[loo2][loo].cost == -1 ) { continue; }
					if ( map[loo2][loo].flag == true ) { continue; }
					if ( map[loo2][loo].cost < minval ) {
						min_x = loo;
						min_y = loo2;
						minval = map[loo2][loo].cost;
					}
				}
			}
			if ( min_x == -1 && min_y == -1 ) { break; }

			map[min_y][min_x].flag = true;

			//up
			if ( yokokabe[min_y][min_x] == 0 && map[min_y-1][min_x].cost > map[min_y][min_x].cost +1 ) {
				map[min_y-1][min_x].cost = map[min_y][min_x].cost + 1;
			}

			//down
			if ( yokokabe[min_y+1][min_x] == 0 && map[min_y+1][min_x].cost > map[min_y][min_x].cost +1 ) {
				map[min_y+1][min_x].cost = map[min_y][min_x].cost + 1;
			}

			//left
			if ( tatekabe[min_y][min_x] == 0 && map[min_y][min_x-1].cost > map[min_y][min_x].cost +1 ) {
				map[min_y][min_x-1].cost = map[min_y][min_x].cost + 1;
			}

			//right
			if ( tatekabe[min_y][min_x+1] == 0 && map[min_y][min_x+1].cost > map[min_y][min_x].cost +1 ) {
				map[min_y][min_x+1].cost = map[min_y][min_x].cost + 1;
			}
		}

		if ( map[height-1][width-1].cost == INT_MAX ) { puts("0"); }
		else { printf("%d\n", map[height-1][width-1].cost+1 ); }

		/*
		for ( int loo2 = 0; loo2<height; loo2++ ) {
			for ( int loo=0; loo<width; loo++ ) {
				printf("%d ", map[loo2][loo]);
			}
			printf("\n");
		}
		*/
	
	}
	return 0;
}

C++: #include <iostream>
#include <queue>
#include <cstring>
#include <climits>
#include <cstdio>

using namespace std;

#define pii pair<int, int>

enum {U, R, D, L};

int main() {
  int w, h;
  while (cin >> w >> h && w + h) {
    int wall[w][h][4];
    
    memset(wall, 0, sizeof(wall));
 
    for (int i = 0; i < w; i++) {
      wall[i][0][U] = 1;
      wall[i][h-1][D] = 1;
    }
    for (int i = 0; i < h; i++) {
      wall[0][i][L] = 1;
      wall[w-1][i][R] = 1;
    }

    for (int i = 0; i < 2*h-1; i++) {
      int wf;
      if (i%2 == 0) {
        for (int j = 0; j < w - 1; j++) {
          cin >> wf;
          if (wf) wall[j][i/2][R] = wall[j+1][i/2][L] = 1;
        }
      } else {
        for (int j = 0; j < w; j++) {
          cin >> wf;
          if (wf) wall[j][i/2][D] = wall[j][i/2+1][U] = 1;
        }
      }
    }
    
    queue<pii > Q;
    Q.push(pii(0, 0));

    int mpath[w][h];
    memset(mpath, 0, sizeof(mpath));
    mpath[0][0] = 1;
    
    while (!Q.empty()) {

      pii now = Q.front();
      int x = now.first, y = now.second;
    
      Q.pop();
      
      const int dx[4] = {0, 1, 0, -1};
      const int dy[4] = {-1, 0, 1, 0};
      
      for (int i = 0; i < 4; i++) {
        if (!wall[x][y][i] && !mpath[x+dx[i]][y+dy[i]]) {
          Q.push(pii(x+dx[i], y+dy[i]));
          mpath[x+dx[i]][y+dy[i]] = mpath[x][y] + 1;
        }
      }
    }

    cout << mpath[w-1][h-1]  << endl;
  }
}