#include<bits/stdc++.h>
#define ll long long 
using namespace std;
string s[52];
ll dis[52*52*16+10],head[52*52*16+10],tot,answer,n,m;
struct kkk
{
    ll to,next,len;
}e[60000007];
inline ll f(ll x,ll y,ll s0,ll s1,ll s2,ll s3)
{
//    cout<<x<<' '<<y<<' '<<s0<<' '<<s1<<' '<<s2<<' '<<s3<<endl;
    return x*51*16+y*16+s3*8+s2*4+s1*2+s0;
}
inline void add(ll x,ll y,ll len)
{
//    cout<<x<<"->"<<y<<':'<<len<<endl;
    tot++;
    e[tot].to=y;
    e[tot].next=head[x];
    e[tot].len=len;
    head[x]=tot;
}
struct kk
{
    ll lo,x;
    kk(){}
    kk(ll a,ll b)
    {
        lo=a;
        x=b;
    }
    inline bool operator<(const kk &p)const
    {
        return x>p.x;
    }
};
priority_queue<kk>P;
void solve()
{
    cin >> n >> m;
//    cout<<n<<' '<<m<<endl;
    for(ll i=1;i<=n;i++)
    {
        cin>>s[i];
        s[i]="."+s[i];
    }
    memset(dis,127,sizeof(dis));
    for(ll i=0;i<=n;i++)
    {
        for(ll j=0;j<=m;j++)
        {
//            cout<<"IJ:"<<i<<' '<<j<<endl;
            ll st[4];
            for(ll k=0;k<16;k++)
            {
                ll p=k;
                st[0]=p%2;p/=2;
                st[1]=p%2;p/=2;
                st[2]=p%2;p/=2;
                st[3]=p;
//                cout<<k<<" SELF\n";
                for(ll o=0;o<=3;o++)
                {
                    if(st[o]==1)
                    {
                        ll stt[4]={st[0],st[1],st[2],st[3]};
                        stt[o]--;
                        add(f(i,j,st[0],st[1],st[2],st[3]),f(i,j,stt[0],stt[1],stt[2],stt[3]),1);
                    }
                }
//                cout<<"SWITCH\n";
                if(st[0]==0&&st[3]==0&&j<m)
                {
                    ll x,y;
                    if(i>=1&&j+2<=m&&s[i][j+2]=='#')x=1;
                    else x=0;
                    if(i+1<=n&&j+2<=m&&s[i+1][j+2]=='#')y=1;
                    else y=0;
                    add(f(i,j,st[0],st[1],st[2],st[3]),f(i,j+1,x,0,0,y),0);
                }
                if(st[0]==0&&st[1]==0&&i>0)
                {
                    ll x,y;
                    if(i-1>=1&&j+1<=m&&s[i-1][j+1]=='#')x=1;
                    else x=0;
                    if(i-1>=1&&j>=1&&s[i-1][j]=='#')y=1;
                    else y=0;
                    add(f(i,j,st[0],st[1],st[2],st[3]),f(i-1,j,x,y,0,0),0);
                }
                if(st[1]==0&&st[2]==0&&j>0)
                {
                    ll x,y;
                    if(i>=1&&j-1>=1&&s[i][j-1]=='#')x=1;
                    else x=0;
                    if(i+1<=n&&j-1>=1&&s[i+1][j-1]=='#')y=1;
                    else y=0;
                    add(f(i,j,st[0],st[1],st[2],st[3]),f(i,j-1,0,x,y,0),0);
                }
                if(st[2]==0&&st[3]==0&&i<n)
                {
                    ll x,y;
                    if(i+2<=n&&j>=1&&s[i+2][j]=='#')x=1;
                    else x=0;
                    if(i+2<=n&&j+1<=m&&s[i+2][j+1]=='#')y=1;
                    else y=0;
                    add(f(i,j,st[0],st[1],st[2],st[3]),f(i+1,j,0,0,x,y),0);
                }
            }
        }
    }
    ll ss=0;
    if(s[1][1]=='#')ss=8;
    P.push(kk(ss,0));
    answer=dis[0];
    while(!P.empty())
    {
        ll lo=P.top().lo,x=P.top().x;
        P.pop();
        if(x>=dis[lo])continue;
//        cout<<lo<<'-'<<x<<endl;
        dis[lo]=x;
        for(ll i=head[lo];i;i=e[i].next)
        {
            ll to=e[i].to;
            if(dis[to]>dis[lo]+e[i].len)
            {
                dis[to]=dis[lo]+e[i].len+1;
                P.push(kk(to,dis[to]-1));
            }
        }
    }
    for(ll i=0;i<16;i++)
    {
        answer=min(answer,dis[n*51*16+m*16+i]);
    }
    cout<<answer;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    ll T = 1;
    while(T--)
    {
        solve();
    }
    return 0;
}