#include <bits/stdc++.h>
#include <unistd.h>

using namespace std;

#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}


typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const ll MOD = 1000000007;
//const ll MOD = 998244353;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { 1,0, -1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
//#define mp make_pair


int main() {
  while (true) {
    int w, h;
    cin >> w >> h;
    if (w == 0) return 0;
    vii l(h, vi(w)), r(h, vi(w)), u(h, vi(w)), d(h, vi(w));
    
    rep (i, h) {
      rep (j, w - 1) {
        int a;
        cin >> a;
        if (a) {
          r[i][j] = l[i][j + 1] = 1;
        }
      }
      if (i == h - 1) break;
      rep (j, w) {
        int a;
        cin >> a;
        if (a) {
          d[i][j] = u[i + 1][j] = 1;
        }
      }
    }

    rep (i, h) {
      rep (j, w) {
        if (i == 0) u[i][j] = 1;
        if (i == h - 1) d[i][j] = 1;
        if (j == 0) l[i][j] = 1;
        if (j == w - 1) r[i][j] = 1;
      }
    }

    vii dist(h, vi(w, inf));
    dist[0][0] = 0;
    queue<pair<int, pii>> qu;
    qu.push({0, pii(0, 0)});
    while (!qu.empty()) {
      int c = qu.front().first;
      int i0 = qu.front().second.first, j0 = qu.front().second.second;
      qu.pop();
      if (dist[i0][j0] < c) continue;
      if (!u[i0][j0] && dist[i0 - 1][j0] > c + 1) {
        dist[i0 - 1][j0] = c + 1;
        qu.push({c + 1, pii(i0 - 1, j0)});
      }
      if (!d[i0][j0] && dist[i0 + 1][j0] > c + 1) {
        dist[i0 + 1][j0] = c + 1;
        qu.push({c + 1, pii(i0 + 1, j0)});
      }
      if (!l[i0][j0] && dist[i0][j0 - 1] > c + 1) {
        dist[i0][j0 - 1] = c + 1;
        qu.push({c + 1, pii(i0, j0 - 1)});
      }
      if (!r[i0][j0] && dist[i0][j0 + 1] > c + 1) {
        dist[i0][j0 + 1] = c + 1;
        qu.push({c + 1, pii(i0, j0 + 1)});
      }
    }

    if (dist[h - 1][w - 1] == inf) {
      cout << 0 << endl;
    }
    else {
      cout << dist[h - 1][w - 1] + 1 << endl;
    }
  }
}



Measured memory_bytes: 3144