#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define endl '\n'
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep2(i,a,b) for(int i=int(a);i<int(b);i++)
#define pb emplace_back
#define all(x) (x).begin(),(x).end()
int mod=1e9+7;
int mod2=998244353;
const int INF=1e9;
//g++ -std=c++11 a.cpp

signed main(){
	ll w,h;
    while(1){
        cin>>w>>h;
        if(!h&&!w)break;
        vector<vector<ll> > wallh(h,vector<ll>(w,0));
        vector<vector<ll> > wallw(h,vector<ll>(w,0));
        rep(i,h*2-1){
            if(i%2==0){
                rep(j,w-1)cin>>wallw[i/2][j];
            }else{
                rep(j,w)cin>>wallh[i/2][j];
            }
        }
        vector<vector<ll> > ans(h,vector<ll>(w,1e9));
        ans[0][0]=1;
        queue<ll> x;
        queue<ll> y;
        x.push(0);
        y.push(0);
        ll px[]={0,1,0,-1};
        ll py[]={1,0,-1,0};
        
        while(!x.empty()){
            ll nx=x.front();
            x.pop();
            ll ny=y.front();
            y.pop();
            rep(i,4){
                ll mx=nx+px[i];
                ll my=ny+py[i];
                if(mx>=0&&my>=0&&mx<w&&my<h){
                    if((nx!=mx&&wallw[ny][min(nx,mx)]==0)||(ny!=my&&wallh[min(my,ny)][nx]==0)){
                        if(ans[ny][nx]+1<ans[my][mx]){
                            ans[my][mx]=ans[ny][nx]+1;
                            x.push(mx);
                            y.push(my);
                        }
                    }
                }
            }
        }
        if(ans[h-1][w-1]==1e9)cout<<0<<endl;
        else cout<<ans[h-1][w-1]<<endl;
    }
}

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