#include <bits/stdc++.h>
using namespace std;
#define int long long
using ll=long long;
using vi=vector<int>;
using vl=vector<long long>;
using pii=pair<int,int>;
using pll=pair<long long,long long>;
#define ITR(i,c) for(auto i=begin(c);i!=end(c);++i)
#define FORE(x,c) for(auto &x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define REPW(i,n) for(i=0;i<(int)(n);++i)
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)   // c++14
#define SZ(c) ((int)c.size())
#define EXIST(c,x) (c.find(x)!=end(c))
#define OUTOFRANGE(y,x,h,w) (y<0||x<0||y>=h||x>=w)
#define dump(...)
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
#define INF (1001001001)
#define INFLL (1001001001001001001ll)
template<class T> ostream& operator << (ostream &os,const vector<T> &v) {
    ITR(i,v) os << *i << (i==end(v)-1 ? "" : "\n"); return os; }
template<class T> istream& operator >> (istream &is,vector<T> &v) {
    ITR(i,v) is >> * i; return is; }
template<class T> istream& operator >> (istream &is, pair<T,T> &p) {
        is >> p.first >> p.second; return is; }
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(b<a){a=b;return 1;}return 0;}
//------------------------------------------------------------------------------
struct before_main_function {
    before_main_function() {
        #ifdef int
            #undef INF
            #define INF INFLL
            #define stoi stoll
        #endif
        cin.tie(0);ios::sync_with_stdio(false);
        cout<<setprecision(15)<<fixed;
    }
} before_main_function;
//------------------------------------------------------------------------------

void solve(int W,int H) {
    vector<vector<bool>> wall(H*2-1);
    bool t;
    REP(i,H*2-1) {
        if(i%2==0) {
            REP(j,W-1) {
                cin>>t;
                wall[i].push_back(t);
            }
        }
        else {
            REP(j,W) {
                cin>>t;
                wall[i].push_back(t);
            }
        }
    }

    vector<vector<bool>> vis(H,vector<bool>(W,false));
    queue<pair<pii,int>> q;
    q.push({{0,0},1});
    vis[0][0]=true;
    while(!q.empty()) {
        int y=q.front().first.first;
        int x=q.front().first.second;
        int d=q.front().second;
        q.pop();

        if(y==H-1 && x==W-1) {
            cout<<d<<endl;
            return;
        }

        int yy,xx;

        // up
        yy=y+DY[0];
        xx=x+DX[0];
        if(!OUTOFRANGE(yy,xx,H,W) && !vis[yy][xx]) {
            if(!wall[y*2-1][x]) {
                q.push({{yy,xx},d+1});
                vis[yy][xx]=true;
            }
        }

        // right
        yy=y+DY[1];
        xx=x+DX[1];
        if(!OUTOFRANGE(yy,xx,H,W) && !vis[yy][xx]) {
            if(!wall[y*2][x]) {
                q.push({{yy,xx},d+1});
                vis[yy][xx]=true;
            }
        }

        // down
        yy=y+DY[2];
        xx=x+DX[2];
        if(!OUTOFRANGE(yy,xx,H,W) && !vis[yy][xx]) {
            if(!wall[(y+1)*2-1][x]) {
                q.push({{yy,xx},d+1});
                vis[yy][xx]=true;
            }
        }

        // left
        yy=y+DY[3];
        xx=x+DX[3];
        if(!OUTOFRANGE(yy,xx,H,W) && !vis[yy][xx]) {
            if(!wall[y*2][x-1]) {
                q.push({{yy,xx},d+1});
                vis[yy][xx]=true;
            }
        }
    }
    cout<<0<<endl;
    return;
}
signed main() {
    while(1) {
        int W,H;
        cin>>W>>H;
        if(W+H==0) break;
        solve(W,H);
    }
    return 0;
}

Measured memory_bytes: 3144